Pep Guardiola has admitted that Manchester City’s inability to maintain a two‑goal lead against Manchester United could weigh on players’ minds when seeking to overturn a 3-0 deficit against Liverpool in the Champions League quarter-final second leg on Tuesday night.

City led 2-0 at the Etihad Stadium on Saturday through goals by Vincent Kompany and Ilkay Gündogan. Yet after the break City crumbled as two Paul Pogba strikes and Chris Smalling’s 69th-minute winner ensured Guardiola’s team failed to win and thus missed a chance to claim the title.

City were also shaky in the 3-0 defeat at Liverpool in the Champions League first leg last Wednesday and Guardiola is conscious that their aim to progress to the semi-finals has been made more difficult after the scars of the past week. If Liverpool score once City would need five goals to knock out Jürgen Klopp’s side.

Asked if the memory of City’s collapse on Saturday could affect players’ minds if they were to go two ahead again, Guardiola said: “It’s difficult – difficult for our mood not winning and, yeah, that can happen. But maybe we will improve for the future regarding this – and realise that sometimes it is not enough what you’ve done [and need to do more] to win.

“In the first half against United we tried to do what we’ve done all season but maybe it’s not enough to win at Champions League level or the Premier League. If that’s so I will have to recognise that I’m not good enough or the way we want to play is not able to do that. But I don’t think so because of what we’ve done this season – in the first half [against United], even in moments in the second half, I have to be happy. But when you play against Liverpool or in Europe when you have that momentum you have to close the door. And we didn’t close it against United.”

Guardiola admitted concern at not being able to ensure his teams can maintain focus. “I thought many times about that. I’ve dropped a lot of Champions League games in the space of 10 or 15 minutes,” he said, offering an example of when he was Bayern Munich manager for a Champions League semi-final first leg in May 2015. “We were playing Barcelona and after 77 minutes it was 0-0, then after 90 minutes – 3-0. This has happened many times – maybe it’s my fault. I have to think about it.”

Last year City allowed a 5-3 last‑16 first-leg lead over Monaco slip to a 6-6 aggregate defeat after the away leg and so were eliminated on away goals. Yet Guardiola did strike a defiant note. “When you dominate and create chances you are closer to winning games and this season showed that. But it’s impossible when opponents arrive four times and score three goals [like United] – there is no system that can stop that, so it is so complicated.”

At Anfield the City manager dropped Raheem Sterling to play an extra midfielder in Gündogan. Against United he left Gabriel Jesus and Sergio Agüero on the bench, so started with no recognised No 9. Asked if those selections had been two errors, Guardiola said: “The first half [going two ahead] was a mistake? OK, we lost, I’m not right, you are right.”

Sterling had missed several chances before the interval, and Guardiola said: “But he was there [for them]. We could be better but we could be worse.

“Always when you don’t win you will have made mistakes but the first half was good. The second was not. But we played three days ago, our physicality was lower than United’s. Maybe the second half was a bit influenced by that. But football is a results business and the result was not good. I would like to correct that, to improve these kind of situations.

“We kept going but when you have two one-against-ones [Sterling] and the Gündogan chance then if we go to 3-0, 4-0 the game is over. But at 2-0 the game is never over, especially in this league. Football at this level is about the [penalty] boxes. Real Madrid and Barcelona are always successful because they have players up front who, when they have half-chances, score two goals. To score goals is the most difficult thing.”