At the end of what Sir Alex Ferguson called a black week for Manchester United, a routine victory against a side that rarely spring any surprises beyond the Black Country was most welcome. Mainly because of the three points that cuts Manchester City's lead at the top of the table to just two, with the leaders facing a testing trip to Chelsea on Monday.

"You always hope that puts them under a little more pressure," said Ferguson, now in the business of seeking out any silver lining. "The main thing is that we are still in touch. If we can get to New Year's Day still in the frame we will be well placed to push on from there."

Wolves are the ideal opponents to play when you are looking for a result to pull yourself out of a slump, as Chelsea discovered a couple of weeks ago. Away from home at least, they defend deep but not particularly well; they rarely cross the halfway line with much conviction; and once behind they tend to accept their fate meekly and opt for damage limitation.

One does not want to be too harsh on a side fighting for survival at the bottom end of the table, but Mick McCarthy's players competed more convincingly than this when the manager infamously changed his entire side for this fixture the season they returned to the Premier League. If he is not careful McCarthy could get into trouble all over again for fielding his real team. "That's what you get when you go full-strength against them," the Wolves manager said afterwards.

"I thought we were still in the game at half-time, but they have better players than us. We were a bit unlucky with some of the goals, shots through players' legs, goalkeeper unsighted, but the result tells the story. Manchester United at Old Trafford is never an easy task, whatever the circumstances."

United were able to attack more or less at will from the start, and though a heavy pitch slowed them up slightly they were soon peppering Wayne Hennessey's goal. Nani rolled a shot across the face of goal, then Michael Carrick headed narrowly over from Antonio Valencia's cross, before Wayne Rooney brought the goalkeeper's first save of the afternoon after just managing to stay onside to gather Carrick's pass.

That was all in the opening quarter, so no one could say it was any sort of surprise when United went ahead in the 17th minute, Nani collecting Valencia's pass and running unchallenged across the edge of the area parallel to the goalline until he spied his chance to beat Hennessey with a low shot. United almost scored again immediately, the impressive Phil Jones just failing to get on the end of a smart passing move involving Rooney, Danny Welbeck and Nani.

With the visiting defenders resigning themselves to a long afternoon, it appeared the only point of interest in the rest of the game would be whether Rooney would break his goal drought or set an unwanted personal record of going nine Premier League matches without scoring. Even that matter was settled after a mere four more minutes of suspense. Rooney, taking his cue from Nani, from whom he also received the ball, beat Hennessey from the edge of the area after Karl Henry was a fraction too late in closing him down.

Wolves managed to make it to the interval without further mishap, and even contributed an unexpected twist to the script by pulling a goal back right at the start of the second half, though for all the ease with which Matt Jarvis beat Chris Smalling and the poise Steven Fletcher showed in climbing above Patrice Evra to nod in his cross at the far post, by the time the game was just over an hour old the visitors had shipped another two goals to the same two players.

Nani turned in Valencia's cross from the right after Jones had worked the ball wide, then from a slightly deeper cross from the Ecuador winger Rooney scored with a half-volley from the back of the penalty area.

Rooney could have ended up with a hat-trick had he received the ball after another galloping break by Jones; he was unmarked and waiting for a far post tap-in from the midfielder's cross but Federico Macheda went for it at the near post and only succeeded in diverting the ball against a defender.

If it was all rather too easy for the Premier League champions – for some reason the Old Trafford announcer kept stressing the fact that United did manage to win something as recently as last season – at least Jones and Valencia put in solid performances and Rooney looked back to something like a quarter of his normal self. Welbeck in front of goal and Smalling when confronted by the tricky Jarvis were perhaps less impressive, but this was small beer instead of the expected champagne.

Roy Keane does not reserve either his praise or his scorn for performances against teams such as Wolves. United want to be measured against the best in Europe. They just face a longish wait, based on their results against Basel and Benfica.