Callum Hudson-Odoi has been told he will not be sold by Chelsea – either before Thursday’s transfer deadline or in the summer.
The 18-year-old, whose contract runs until June 2020, is wanted by Bayern Munich.
Chelsea have turned down a transfer request from Hudson-Odoi and head coach Maurizio Sarri has made it clear the player will not be allowed to leave.
Sarri said: “On the pitch he’s doing very well. I’m really very happy with him. I’m not very happy with the situation, but I know very well that every big team here in England has the same problem.
“It’s not easy to keep these young players. He is of course one of the best 18-year-old players in Europe, so it’s very, very difficult.
“The club told me he’s out of the market for sure and probably he will be out of the market in July.”
Hudson-Odoi scored his second Chelsea goal on his sixth start of the season in Sunday’s FA Cup fourth-round win over Sheffield Wednesday.
He is yet to start in the Premier League and has made just three substitute appearances in the top flight, the first coming on Boxing Day at Watford.
Speaking ahead of Wednesday’s Premier League clash at Bournemouth, Sarri added: “He’s improving. I think he’ll be the future of our club. He will be the future of English football.”
Hudson-Odoi has been offered a new contract by the club but has indicated that he will not sign it and that he is keen to join Bayern.
Sarri said: “I cannot do anything, as you know very well. If I have the power to sign a new contract, I can do everything.
“It’s impossible to promise him that he will play every match, because it depends on the situation.”