Roberto de Zerbi says Carlos Baleba must progress quickly after pitching him into his midfield.

The 19-year-old midfielder produced a mixed performance in the 1-0 defeat at Chelsea.

But De Zerbi believes the experience – in a Carabao Cup tie but essentially a Premier League-type environment – will serve him well.

He highlighted the adaptation his summer signing must make after moving from Lille.

De Zerbi said: “You are used to watching, I think, only the Premier League games.

“But the other European leagues are totally different to the Premier League.

“The Premier League is stronger, is tougher and the new players have to adapt to the difficulty during the game.

“He is 2004 (year of birth). It was the first game in his life in the first XI in Premier League at Stamford Bridge.

“I am pleased with his performance.

“Clearly he has to improve, he has to progress. Maybe now he is not so ready to play in the first XI.

“We lost Pascal Gross and James Milner and so in that position we are only three midfielders.

“But the players have to adapt and the coach has to adapt.

“In this moment we are playing a lot of games.

“I don’t want to make any excuses.

“The younger players have to progress quickly.”