Diego Costa was hospitalised with a rib injury sustained at Stoke, with Jose Mourinho saying the striker “punched himself”.
Costa was substituted after 32 minutes of the Capital One Cup clash at the Britannia, which Chelsea ultimately lost on penalties.
When asked about Costa, Mourinho said: “He is in the hospital – I don’t know.”
The Chelsea boss also admitted that he did not know whether the Spaniard would be available for the meeting with Liverpool on Sunday as the Blues seek to arrest a run of form that has seen them lose half of their 10 Premier League matches so far this season.
Costa was withdrawn not long after being sandwiched between Ryan Shawcross and Charlie Adam in a tackle before attempting to reach a Willian cross that was punched away by Stoke goalkeeper Jack Butland.
“I think he punched himself,” Mourinho added.