Chelsea'a Chukwuemeka undergoes knee surgery
"Carney Chukwuemeka sustained an injury to his left knee during our game against West Ham United on Sunday," said a statement on Chelsea's website.
"Last (Monday) night Carney underwent surgery and will now begin his recovery.
"The 19-year-old will work with the club's medical department on his rehabilitation at Cobham."
No timeline has been put on the absence of Chukwuemeka, who scored his first goal for Chelsea in their 3-1 loss away to London rivals West Ham in the Premier League, but he could be out of action for up to six weeks.
The former Aston Villa midfielder found first-team game time hard to come by last season following his £20 million ($26 million, 23 million euros) move.
Chukwuemeka has, however, started both of new Chelsea manager Mauricio Pochettino's first two Premier League games in charge.
He had surgery after being withdrawn 15 minutes from the end of Chelsea's loss at the London Stadium, the first defeat of Pochettino's reign as Blues boss.
Earlier, he had drawn Chelsea level, following Nayef Aguerd's header, when he cut inside and struck a fierce right-footed shot past goalkeeper Alphonse Areola.
It was his first goal in 17 appearances in all competitions since arriving at Stamford Bridge.
The Hammers went on to win the game in the second half with a goal from Michail Antonio and a penalty from Lucas Paqueta, after Chelsesa's Enzo Fernandez saw his penalty saved.