But, asked if Sane was at his best, Guardiola said: "No. After the first goal, yes. Before, no. He was not aggressive enough in the first 20 minutes.

"I like when he runs and goes. If he loses the ball, it doesn't matter. It is the same with Raheem (Sterling) but they are young.

"I know it is tough for Leroy, he doesn't play every game, but after 20 minutes he was then outstanding for the goal and the assists.

"He is a player we know has incredible qualities. It is difficult to find around the world a player with the qualities he has."

Sergio Aguero began the rout with two goals while Sterling, Bernardo Silva, Phil Foden and Gabriel Jesus also got on the scoresheet.

City will find out who they play in the last eight on Friday. Two of Guardiola's former clubs – Barcelona and Bayern Munich – could join them if they come through their ties on Wednesday. Bayern face City's chief title rivals Liverpool.

Asked which of those two sides he might prefer, Guardiola said: "I'm sorry for the English people but I want Bayern to go through. I am big fan, I am part of this club. I love Munich, Bayern and all the people. I would like Bayern to go through but it will not be easy."

Guardiola had described City as "teenagers" in Champions League terms on the eve of the match but their convincing victory was a strong statement to the rest of the competition.

The City boss said: "When I said we are a teenage team, I didn't say we are not going to fight. We are going to try.

"If it doesn't work, I am sorry, but I assure you next season we are going to try.

"This competition is incredibly tough, there are incredible teams, so when we are through the group stages I am happy. It is so nice to be in the quarter-finals for the third time in our history."

Schalke's humiliating loss could spell the end for their under-fire manager Domenico Tedesco. With his side struggling in the Bundesliga, Tedesco had reportedly been on the brink of the sack heading into the game.

Tedesco said: "I'm extremely disappointed. We fell apart. There was a lack of tension and it was the worst we've had here since I was coach.

"Of course it hurts and it's difficult to stand here when you lose four, five, six, seven-nil but that's why I'm here – not just in good times but in situations where it's less fun. It really hurts today."

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