Pep Guardiola was unhappy with his team's performance, despite Manchester City's progression past Atletico Madrid to the Champions League semi-finals on Wednesday.

Following their 1-0 win in the first leg, City advanced with a goalless draw at the Wanda Metropolitano on Wednesday, but they were increasingly on the back foot as the second leg progressed.

There was a prevailing sense Atleti would be the team to find a higher gear in the second half, and if not for some desperate City defending once pinned in their own half, the tie could have gone to extra time at the very least.

Guardiola admitted City were fortunate to progress against an Atleti side well-prepared by Diego Simeone, especially as the closing exchanges grew more frenetic.

"They [Atletico] played very well, they put us in our own half and there was no way out. We had forgotten how to play," Guardiola told Movistar+ post-match. "We're celebrating but we could very well have been eliminated. Atletico played a great second half.

"Today we could have been knocked out of a competition and luckily we continue. They were very good and when they push, it can be very complicated. We resisted, but it could have fallen the other way.

"The coaches from the sidelines, with the atmosphere, the players don't listen to us. They were just trying to control the ball, but we didn't control the ball and when you don't control the ball, they can use it very well."

Guardiola's side never really clicked on Wednesday, even after Bernardo Silva and Phil Foden switched positions to give City greater presence in the centre of pitch.

Once the likes of Rodrigo de Paul and Angel Correa came on for Atleti, there was an outlet and end product to their dominance between the penalty areas.

Along with the performance, City will now be without Joao Cancelo when they face Real Madrid in the semi-finals, while Kyle Walker and Kevin de Bruyne came off injured.

The 51-year-old coach understands, however, simplicity is a luxury at this stage of the competition.

"The only thing missing is if it wasn't complicated," he said. "The king of the competition. It's the third semi-final in our history in the Champions League.

"We've repeated last year's and it's a success for us. If we play like we did in the second half on the other hand, we will not have a choice. We will try to raise our level."