Chelsea manager Enzo Maresca has confirmed a hamstring injury will rule centre-back Wesley Fofana out for the rest of the season.
On Saturday, the club confirmed the 24-year-old France defender had undergone "successful surgery".
While Chelsea will have to do without Fofana, Maresca is hopeful midfielder Romeo Lavia and striker Marc Guiu could play again before the end of the campaign.
"Unfortunately, Wes will be out for the rest of the season," said the Blues boss, before Thursday's Europa Conference League quarter-final first leg in Poland against Legia Warsaw.
"Hopefully we can get [back] Romeo very soon.