Chelsea boss Maurizio Sarri says injured midfielder Ruben Loftus-Cheek will be out for four to six months.
The player has had surgery after rupturing his Achilles tendon during a friendly in Boston last week, ruling him out of the Europa League final.
"The conditions in Boston were not very good but there is not only one cause for the injury," said Sarri.
"It is a similar injury to what Callum Hudson-Odoi [is suffering with] and the recovery time is almost the same."