Russell Martin: “I think the penalty miss has changed the whole game,” says Southampton’s manager in an interview with TNT Sports. “I thought we were great up until then, we played really, really well and I was really happy with so much of the performance.

“We didn’t respond very well to the penalty miss and the goals are nonsense – two second phase set plays, which is frustrating because there really wasn’t very much in it at that point.

“And then the second half is both teams not really gertting any grip on the game but really trying. Then we had a man sent off and it was about damage limitation at that point, so I’m really frustrated that we conceded the third goal.

“So there was so much good stuff and there was plenty to be pleased about in that first half but the penalty miss just changed the whole atmosphere around the game.”

Erik ten Hag: “The start was not easy,” says Manchester United’s manager in an interview with the BBC. “I think the penalty was the turning point in the game. From that moment on, the game was all ours.”

On Matthijs de Ligt playing well: “I’m not surprised,” he says. “At this moment he is not fit, he’s not at 100% speed. He needs the games to go up to it. We see glimpses now and once he’s there he will do much better. We are happy with him and especially today with his game.”

On Marcus Rashford’s goal: “It’s very important. For every striker, they want to be on the scoring list. Once the first is in, more is coming. Once a striker was talking about a ketchup bottle: once it’s going, it’s coming more.”

On Manuel Ugarte: “He didn’t work with the team, it was two sessions, one before the break and yesterday. He was the only one later into the team training [after the international break] so only yesterday he had 20 minutes training with the team. We were happy we could bring him today and show what he could deliver to our team.”

An email: “Given the significance of Onana’s penalty save in United going on to win so comfortably, should the goalkeeper be the player of the match even though he had pretty much nothing to do in the hour following that?” asks David Wall.

I can see where you’re coming from but the fact of the matter is that Cameron Archer’s penalty didn’t take much saving. It was really terrible, although I do appreciate Onana can only save the shot that’s fired at him, I don’t think he will begrudge Matthijs de Ligt the luminous yellow perspex cuboid he’s just been handed by TNT Sports touchline reporter Jules Breach.

Matthijs de Ligt: “Today we played really well although we had some trouble at the beginning,” he tells TNT SPorts. “It was a big credit to Andre [Onana] who saved a really important penalty. He changed the game for us.”

On his goal: “We’ve been working on some set-pieces and that one was not exactly out of the book but luckily I was in a good spot.”

90+3 min: We’re halfway through six minutes of added time. Southampton are on course to lose their fourth consecutive top flight game and only have one goal, against Brentford, on the credit side of the ledger so far. Manchester United win a corner but nothing comes of it.

90+1 min: Zirkzee has a shot from close range blocked by the right foot of Taylor Harwood-Bellis from about six yards out. He should have scored but dawdled over his shot after controlling a Dalot pull-back from the byline.

90 min: Garnacho tries to tee up Bruno Fernandes on the edge of the Southampton penalty area but the United captain is unable to sort his feet out in time to get a shot off. Adam Lallana clears.

87 min: Manchester United substitution: Matthijs De Ligt goes off with what looks like cramp and is replaced by Casemiro.

84 min: An exciting first half has been followed by something of a non-event of a second, in which a bamboozled fourth official trying to cope with a quadruple-substitution and the sending-off have been the highlights in terms of entertainment.

After showing so much promise before going behind once Cameron Archer had missed their penalty after 30 minutes, Southampton have been absoutley dismal. That spot-kick seems lik it was a real Sliding Doors moment.

82 min: Southampton have brought on Taylor Harwood-Bellis for Mateus Fernandes and the substitute slots in at centre-back in place of his recently departed skipper.

81 min: Russell Martin gets booked, presumably for protesting about the decision to issue Jack Stephens with a straight red. He can’t have any complaints.

78 min: Man United substitution: Jonny Evans on for Martinez, who doesn’t want to be replaced despite his obvious discomfort.

76 min: Cornet gets on the ball out on the right wing and tries to cut inside, take on and beat Lisandro Martinez. The Argentinian, who is visibly struggling with an injury, is having none of it, stays on his feet and refuses to let him pass.

74 min: Manchester United triple-substitution: Harry Maguire, Alejandro Garnacho and Manuel Ugarte on for Noussair Mazraoui, Christian Eriksen and Marcus Rashford. Almost immediately, Maguire is booked for tapping the ball away Declan Rice-style to prevent Southamtpon taking a quick restart.

71 min: Maxwel Cornet is booked for failing to retreat 10 yards at a free-kick. I think we’ve had three cards dished out in this game so far, all of them for needlessly stupid offences bordering on the outright thick.

70 min: Both teams seem to be just going through the motions and the manner in which Southampton’s players appear to have hoisted the white flag of surrender since half-time will be a source of great concern to their fans.

68 min: Bruno Fernandes boots the ball away Joao Pedro-style after failing to keep it in play and is immediately booked for his troubles. He is not impressed and tells the referee he didn’t hear his whistle after the ball had gone out for a Southampton throw-in.

65 min: Ross Stewart makes his Premier League debut at centre-forward for Southampton. A £10m signing from Sunderland 20 months ago, the Scottish striker only made four substitute appearances for Saints last season, having arrived at St Mary’s with a torn achilles before doing his hamstring a serious mischief.

Southampton substitutions: Adam Lallana, Ross Stewart, Ryan Fraser and Maxwel Cornet on for Brereton Diaz, Archer, Dibling and Ugochukwu.

61 min: The corner comes in and the ball goes out off Downes, under pressure from Rashford. The match officials award a goal-kick.

60 min: Ramdsale leaps to palm the ball over the bar, in doing so preventing Marcus Rashford from scoring with a speculative effort from distance.

58 min: There’s a long way to go in this game but Southampton are already playing like a team that knows it is beaten. And well they might because Manchester United have never lost a Premier League game in which they have led 2-0 and have only drawn five out of 186.

56 min: A bit of a scramble on the edge of the Southampton six-yard box ends with a loose ball being hooked clear after Mazraoui had failed to pounce.

55 min: Sugawara is penalised for barging Marcus Rashford off the ball and pleads his innocence. Nothing comes of the free-kick wide on the left.

54 min: Ben Brereton Diaz boots a speculative ball from midfield into space behind the Manchester United defence but there’s nobody in a Southampton shirt on his wavelength or within 25 yards of the area in which the ball lands.

50 min: United sweep forward in numbers with Rashford on the ball. He takes on Bednarek and gets the ball on to his right foot before shooting high and wide. The ball takes a nick off Bednarek on its way out and United have another corner. Nothing comes of it as Ramsdale gathers Eriksen’s inswinger.

49 min: Mazraoui runs on to a pass in behind from Amad and tries to squeeze the ball home past Ramsdale at the near post. Wide. The United right-back’s reaction suggests he might have actually mis-hit an attempted cross.

48 min: Lisandro Martinez makes a crucial interception as Southampton try to play Dibling in behind down the right.

47 min: United enjoy a period of sustained possession before Ykinari Sugawara wins a throw-in for his side. Most of the early second half action is taking place in the middle third of the pitch, 20 yards either side of the halfway line.

An email: “Dalot looks like an old, half-blind sheepdog trying to corral a young lamb that is giving him the runaround,” writes Justin Kavanagh of the roasting the Manchester United left-back has been getting from Tyler Dibling. “Will Ten Hag put him out of his misery at half-time like he did with Casimiro recently?”

45+1 min: Having played so well for long periods of this first half, things have gone massively pear-shaped for Southampton.

The positivity which permeated throughout St Mary’s as Cameron Archer stood over the ball hoping to put his side 1-0 up from the penalty spot 15 minutes ago has completely evaporated and it could be argued that the home side are now lucky to be only two goals down. It’s half-time.

43 min: Southampton are completely on the ropes. From another corner, the ball is played low into their penalty area and finds its way to an unmarked De Ligt. His shot from eight yards is superbly blocked by Aaron Ramsdale, who probably could have done better with his effort to save Rashford’s shot a couple of minutes previously. We’ll give him the benefit of the doubt and say he was unsighted …

41 min: Rashford, who has not scored since 17 March, is played in behind by Amad and finds himself one-on-one against Ramsdale. Southampton’s goalkeeper comes out on top and concedes another corner.

38 min: Moments before that goal and seconds after Southampton had missed their penalty, Joshua Zirkzee had brought a very smart save indeed out of Ramsdale, who got down well to tip his low shot around the post and concede the corner from which United scored.

37 min: United had a corner, which Christian Eriksen pulled short to Bruno Fernandes in acres of space near the left side of the Southampton penalty area. He had all the time in the world to pick out De Ligt at the far post and the Dutch defender made no mistake.

34 min: Ben Brereton-Diaz looked ready to take the penalty but handed the ball to Cameron Archer. Perhaps that was the plan all along? After Archer placed the ball on the spot, he had a wait of almost a minute before Stuart Attwell gave him permission to take the penalty.

29 min: Amad gets on the ball and canters up the right flank before veering inside and unleashing a shot. The ball takes a big deflection off Jack Stephens before Aaron Ramsdale claims it.

28 min: A Yukinari Sugawara free-kick from the right near the byline is headed over the bar by a criminally unmarked Lesley Ugochukwu.

27 min: Kobee Mainoo goes to ground in a tussle and deliberately handles the ball near the halfway line. He gets booked and his third yellow card of the season is a very cheap one.

25 min: Flynn Downes sends Sugawara on his way down the inside-right and the Japanese international squares the ball across the face of the United penalty area. It’s cleared.

23 min: Facing his own goal, De Ligt sticks out a leg to hook a Sugawara cross from the right clear before it can reach the lurking Cameron Archer. It’s a crucial interception.

22 min: Andre Onana darts off his line to pluck a Kyle Walker-Peters cross into the United penalty area from the air before it can reach Tyler Dibling.

19 min: Bruno Fernades has a shot-come-cross blocked at the conclusion of a United counter-attack after good work along the byline by Southampton’s Kyle Walker-Peters at the other end of the pitch. Sadly for Southampton, his pull-back was cleared by Matthijs De Ligt.

17 min: United win their first corner of the match when Dalot puts the ball out of play off Jan Bednarek. Yukinari Sugawara clears the inswinger at the near post but Noussair Mazraoui catches the ball with a sweet volley from outside the area. The United right-back does well to keep his strike on target but it’s straight at Ramsdale.

14 min: United get forward, with Amad on the ball near the right side of the Southampton penalty area. He plays the ball inside to Christian Eriksen, who plays it towards the far post. Joshua Zirkzee is unable to get enough power on his connection to beat Aaron Ramsdale. That was a chance!

13 min: Bruno Fernandes is the latest United player to lose the ball, coughing up more cheap possession being outmuscled by Lesley Ugochukwu right on the halfway line.

12 min: Matthijs De Ligt stands as firm as Cameron Archer receives the ball to feet near the United six-yard box with his back to goal and tries to turn. Erik ten Hag’s side keep giving the ball away cheaply inside their own half.

11 min: Southampton are visibly growing ino this contest, their confidence buoyed by that early effort from Dibling.

10 min: Ben Brereton-Diaz spots a run from Cameron Archer and plays the ball into his path from deep. Andre Onana is quick off his line to avert the danger on the right side of his penalty area.

7 min: Andre Onana is forced into a great fingertip save from Tyler Dibling, who beats Dalot, canters upfield and unleashes a curled left-footed effort that threatened to creep inside the far post.

6 min: Much maligned for their insistence on playing out from the back, Southampton are showing no signs of being wedded to the policy today. Aaron Ramsdale has clipped three balls long already when atempting to play out from the back under pressure from lurking United players looked risky.

5 min: Marcus Rashford tries to cut inside after running on to a pass up the inside right from Christian Eriksen. Jack Stephens relieves him of the ball and clears.

3 min: It’s a big day for Southampton winger Tyler Dibling, who makes his first Premier League start today. The 18-year-old is a very highly regarded graduate from the Saints academy, who is back at the club after a short spell at Chelsea.

2 min: Southampton have opted for a change in system and line up with a back four and they might have changed their approach a little too. After playing one ball through the centre along the deck, Aaron Ramsdale launches another airborne clearance as far as he can down the middle.

Not long now: Led by match referee Stuart Attwell and his team of assistants, the players of both sides make their way out on to the St Mary’s pitch ahead of the last of the pre-match formalities. It’s a sunny afternoon on the south coast, with condititions more or less perfect.

Erik Ten Hag: In an interview with TNT Sports, the Manchester United manager says Manuel Ugarte is not in his starting line-up because he has not had time to get assimilated into the squad properly yet.

“Manuel, we have to integrate into the team,” he says. “He has only had two sessions, we have to integrate and that takes time.”

On what the presence of Christian Eriksen in the side means for Casemiro: “We have a squad and we offer a lot of games, he will play I am convinced of this.”

Manchester United: Erik ten Hag accepts that if Manchester United’s poor results continue the backing offered by the club’s executive will fade, with the manager admitting: “You have to deliver.” Words: Jamie Jackson.

Manchester United: While a familiar tale of gloom is playing out at Old Trafford, Erik Ten Hag’s future is a distraction from the fact that United face more profound challenges, writes Barney Ronay.

Those teams: Contrary to expectations, there are no starting berths for Manuel Ugarte and Alejandro Garnacho, who are both on the bench after returning from international duty in South America. Christian Eriksen comes into midfield in place of Casemiro, while Amada Diallo is also back in the starting line-up in place of Garnacho.

Russell Martin makes four changes to the Southampton side that lost against Brentford last time out and switches to what looks like a back four. Leslie Ogochukwu, Matheus Fernandes, Tyler Dibling and Cameron Archer come into the side, with Taylor Harwood-Bellis, Joe Aribo and Adam Armstrong all dropping to the bench. Will Smallbone is not in the matchday squad.

Southampton manager Russell Martin has thus far been loyal to the players who helped Southampton to the Premier League but after three consecutive defeats, he says he is ready to hand more opportunities to new recruits such as Cameron Archer, Mateus Fernandes, Maxwel Cornet and Ryan Fraser.

“I have to balance that loyalty and what they did last season with what some are actually doing now and the place they’re in right now,” he said. “Also, with the level of talent that’s come into the building, they need a bit of time to adapt, but we’ve brought in some really brilliant players.

“It’s about trying to get that right for them to come into the team. I think now it’s inevitable that changes will be made and people will have opportunities that they need to take.”

Early team news

Deadline day signing Manuel Ugarte is expected to make his debut for Manchester United today in place of Casemiro, who had a nightmare day at the office against Liverpool. Summer signing Leny Yoro remains sidelined with a leg injury, along with Tyrell Malacia, Mason Mount, Rasmus Hojlund, Luke Shaw and Victor Lindelof.

Goalkeeper Gavin Bazunu and striker Kamaldeen Sulemana are the only confirmed absentees for Southampton, while Ross Stewart is close to a return to full fitness and could feature in today’s squad. The Scottish striker has only played for Southampton four times since making the long trip to the south coast from Sunderland 20 months ago.