Diego Costa could miss Chelsea's clash with Liverpool on Saturday after being taken to hospital with a rib injury sustained in their Capital One Cup defeat to Stoke City.
The Spain international striker, who was Chelsea's top scorer last season, came off after 30 minutes and manager Jose Mourinho is unsure if he will be fit to face Jurgen Klopp's team.
"I don't know," Mourinho said in a news conference. "He is in the hospital."
Costa was substituted shortly after being sandwiched between Ryan Shawcross and Charlie Adam in a tackle and then trying to muscle his way towards a Willian cross that Stoke goalkeeper Jack Butland punched away.
Mourinho joked darkly about how Costa had injured himself, saying: "I think he punched himself in the ribs."
Chelsea lost 5-4 on penalties after a 1-1 draw and Mourinho said he faces a challenge to lift his side for Saturday's game at Stamford Bridge.
But he thinks they should be buoyed by their performance at the Britannia Stadium, especially going forward.
"They go [home] with sadness but a positive feeling," he said. "How can [Eden] Hazard or Oscar or [John Obi] Mikel or John [Terry] -- and I could say everyone -- how can they go home with lack of confidence? Lack of confidence, why? They play well.
"I think they enjoy more playing games than anything before, [because] the attacking players, Eden, Oscar, Willian, how many times do they touch the ball?"
Mourinho claimed his critics are guilty of double standards, explaining: "In my case, in your eyes, results are everything.
"But it is a bit strange because when a few months ago I won so many matches and was champion of England, people were saying there were some things more important than the result. Now results are everything. It is a contradiction."