Maurizio Sarri believes Callum Hudson-Odoi needs to improve significantly before playing Chelsea, amid interest from Bayern Munich.
Reports claimed earlier this week that Bayern were preparing a move for the 18-year-old in January.
However, Sarri sees plenty of areas where the young winger has to improve.
"He has to improve. He has to improve a lot," Sarri said at a press conference ahead of his side's game against PAOK in the Europa League on Thursday.
"First of all, in the defensive phase, he has to work. He has to improve in the offensive phase – he's very good one against one, but he has to learn to move without the ball.
"He is potentially a very good player, and now he has to study and improve and work. But I think that's really very normal. He's 18, so that's normal."