Maurizio Sarri will not allow Ruben Loftus-Cheek to leave Chelsea in January, reports say.
The Chelsea midfielder was thought to be angling for a permanent move in the upcoming winter transfer window, after starting just three games this season.
West Ham want to sign Loftus-Cheek as Manuel Pellegrini aims to steer the Hammers away from a relegation battle.
But the Mirror claim Sarri will block efforts from Loftus-Cheek to exit the club as he feels Chelsea will need the Englishman during the final months of the season.
Loftus-Cheek reminded Sarri of his talents with a hat-trick in the Europa League against BATE Borisov.
The 22-year-old then followed up that performance up with a goal against Burnely in Chelsea next game.
The players agent recently said Loftus-Cheek would be forced to leave Chelsea if his playing time did not improve.
Sarri is yet to hand Loftus-Cheek a Premier League start this season, and West Ham were hoping to pounce on the uncertainty surrounding his future.
Loftus-Cheek spoke out on his future and admitted he understood why some people believe he needs to leave Chelsea.
I hear it a lot, and I can see why people are saying that, because Im 22 now and havent got too many Premier League starts to my name, Loftus-Cheek said.
I havent played too many minutes, whether it be in the Premier League and the Championship, and at 22 its not seen as enough by some people. I do hear it. I love the club and I love Chelsea, I want to play for Chelsea.
Last season [moving to Palace on loan] was a decision I made because I hadnt played any football really, at the age of 21, and last season was great for me at Palace – 24 [appearances] I think I had in the Premier League, and then to go on and make my England debut. I made a lot of steps last year.
Playing football was massive for me and you can see why people want to see me play, and I want to play as well.