Petr Cech dislocated his right shoulder during Tuesday's draw with Atletico Madrid in the Champions League semifinal first leg, and Chelsea manager Jose Mourinho said the goalkeeper will not return this season.
"Cech's season is over," Mourinho told Sky Sport Italia after the 0-0 draw. "He won't play again this term, but I hope he can at least celebrate something with us."
Cech was injured just 16 minutes into the match and was replaced by Mark Schwarzer.
The Chelsea keeper jumped to clear a corner over his own bar but had his legs taken out from under him by a stumbling Raul Garcia. Cech fell awkwardly and immediately grabbed his right arm.
The Madrid hospital that treated Cech tweeted a picture of the goalkeeper signing the guestbook with his left hand.
While Cech's injury has ended his season, there are also doubts over the fitness of skipper John Terry after he appeared to turn an ankle in the second half.
Mourinho revealed Terry would miss at least the second leg, saying, "We have to play the (May 24) final for him to play with us."
The injuries come at a crucial time for Chelsea, who are set to face Liverpool on Sunday with the Premier League title potentially on the line. Liverpool sit five points above Chelsea with three games to play.
The 41-year-old Schwarzer managed to keep a clean sheet on Tuesday, three days after setting a record as the club's oldest player in the Premier League in a 2-1 defeat to Sunderland. Chelsea are facing another of their goalkeepers, Thibaut Courtois, who is on loan to Atletico.
The second leg is at Stamford Bridge next Wednesday, and Mourinho said the Blues face a tough challenge to win a trophy without Cech.
"It will be difficult to do without our goalkeeper," Mourinho said.
Frank Lampard and John Obi Mikel will also miss the second leg to suspension after being booked on Tuesday.