Academy graduate Lewis, who made 23 appearances for City in all competitions last season, was among the Premier League club's best attacking outlets on Wednesday and set up Phil Foden's 25th-minute opener.

Asked about Lewis's performance, Guardiola, who has previously coached the likes of Lionel Messi and Xavi Hernandez, told reporters: "What a player. 18-years-old. I have been a manager for 14, 15 years training unbelievable players.

"To find a player like him playing in the pockets, how he has to move in holding midfield, full back coming inside moving in the spaces - he is one of the best I ever trained by far.

"Today was proof again. This season he hasn't played much but he is going to play a lot."

The win saw City move to six points from two games in Group G and comes after defeats to Wolverhampton Wanderers in the league and Newcastle United in the League Cup.

"Three or four days ago, it was no progress because we lost in Wolves. It was important to break that," Guardiola said.

The Premier League leaders next face third-placed Arsenal on Sunday. The clubs were involved in a two-way battle for the title last season before Arsenal faltered in the run-in.

"We will go to Arsenal to do our game," Guardiola told TNT Sports.

"Hopefully we can arrive in March, April, May being there close to the competitions. I have a feeling we will not be an easy opponent to beat."