Chelsea boss Maurizio Sarri has criticised Bayern Munich after they went on the record about wanting to sign Blues winger Callum Hudson-Odoi.
Bayern have bid £35m for the 18-year-old and their sporting director, Hasan Salihamidzic, has said the German club "really want to sign him".
Hudson-Odoi has 18 months left on his Chelsea deal.
"It's not professional, because they are talking about a player under contract with Chelsea," said Sarri.
"So they didn't respect our club, I think." Chelsea have offered Hudson-Odoi a new deal and Sarri, who said he wants to sign two players in January, reiterated that he wants the teenager to stay at Stamford Bridge.
"We are very happy with the player because he is improving," said the Chelsea manager.
"He is improving a lot I think in the defensive phase. Now, he needs to improve in some movements without the ball.
"He is working very well and I'd like to have him in the future."
Hudson-Odoi, who made his first-team debut in the FA Cup in January last year, made a second successive start in the Carabao Cup first-leg defeat by Tottenham.
He provided assists for two goals in the FA Cup third-round win over Nottingham Forest.
But the FA Youth Cup and Under-17 World Cup winner is yet to start a Premier League game at Chelsea and has made only one top-flight appearance this season.
If the teenager moves to Bayern, he will become the third English teenager currently in the Bundesliga - alongside Jadon Sancho, 18, who left Manchester City for Borussia Dortmund in 2017 , and Reiss Nelson , 19, on loan from Arsenal at Hoffenheim until July.
Eden Hazard, Willian and Pedro are all regulars in Chelsea's starting line-up ahead of Hudson-Odoi, but Sarri recently said he was starting "to consider him at the same level".
He is set to face more competition next season at Stamford Bridge with the £58m arrival of United States winger Christian Pulisic from Borussia Dortmund.