Erik ten Hag questioned the fight and determination of his Manchester United players as their traumatic start to the season continued with a 4-3 Champions League defeat at Bayern Munich – their fourth loss in five matches.

André Onana accepted the blame for the result, saying he had “let the team down” with his handling error for Leroy Sané’s opening goal, which came after United had been the better side for the first 20 minutes or so.

But Ten Hag looked more at the way Sané was allowed to drift inside without challenge, swap passes with Harry Kane and shoot. The United manager was similarly upset at how easily Jamal Musiala was able to set up Serge Gnabry for 2-0.

“The first goal was so easy and it was not only André,” Ten Hag said. “You see how easy Sané was going through and that has to do with determination. You don’t let players through so easy.

“We have to make our own luck and that has to do with determination. No one will bring you anything in football. The second goal … it’s almost similar over on the other side, how easy players come through our box and to finish. It can’t be.

“You have to suffer, sacrifice in situations to stop that and only when we get that in, we’ll win games. When you score three goals in Munich, you have to take a point. You have to look in the mirror because the goals were easy giveaways.”

Ten Hag is in the midst of a selection crisis, with 12 players missing here – nine because of injury. He was asked whether United’s problems were down to the injuries or mentality. “Both,” he replied. “We only get out of this with both.”

Onana was distraught about his mistake and he requested to speak to the media. “We started very well and after my mistake we lost control of the game,” he said. “I let the team down. It’s because of me we didn’t win this game.

“They hadn’t created any chances and their first shot on target … I made the mistake and the team went down. We fought until the end but I have to recognise that we didn’t win because of me. I still have a lot to prove. My start [at United] hasn’t been so good, not how I wanted.”