Victor Lindelof admits Manchester United did not play at their highest level in the exhausting Europa League quarter-final win over Copenhagen.

United needed an extra-time penalty from Bruno Fernandes to prevail against the Danish side and set up a semi-final with either Wolves or Sevilla in Cologne on Sunday.

Lindelof did not start the last-eight tie but was introduced midway through the second-half for Eric Bailly and the Swede could not put his finger on why United toiled.

"It was a tough game but we came through in the end and we're happy for that," Lindelof said. "I mean, we knew what kind of team they were and I think they made it difficult for us today, even if we didn't play at our level today.

"I think we could have done a lot of things better but when we had the ball they made it difficult for us. Sometimes they pressed high and when they didn't they dropped deep and defended compact as a unit. It was hard to create some chances there but I think we should have scored a few more goals.

"It's very difficult to say just why. It happens sometimes in football. Of course it's been a long season but we played a quarter-final in a European cup, so I think everyone had to be ready for that.

"Like I said, it happens sometimes in football that you don't perform at the level you want to. But the important thing is that we won and we're through to the semi-finals."

United's performances over the last month have not been convincing but they still secured third in the Premier League and reached their third semi-final of the season in Germany.

Lindelof is yet to win a trophy with the club that he joined in 2017 and is convinced United can achieve 'great things' soon.

"I think we have a lot of confidence in the team right now," the Swede added. "We've been performing on a very high level, especially after the league ended. We got the third spot and we've been some performing some really, really good football. I think everybody has a lot of confidence and we know we can do some great things.

"Obviously even if we play against Sevilla or Wolves, they are two tough teams but we're going to be ready and hopefully we can go out and perform a really, really good game.

"It's always been our goal to win this competition and we want to go through to the final. We've been playing a few semi-finals this season and hopefully we can win the next game and get through to the final. That has always been our goal."