Chelsea have released a statement confirming that centre back Antonio Rudiger has undergone a successful operation on the knee injury he picked up during last Sunday's 1-1 draw with Manchester United.
The 26-year-old suffered a problem in his left meniscus during the second half at Old Trafford and was unable to continue, eventually being replaced by Andreas Christensen after 63 minutes.
The club have confirmed on their official website that Rudiger will now be missing for the rest of this season, with the Blues still to play at least four more matches, which could increase to five if they reach the Europa League final.
The Germany international had only just returned to the side following a two-game absence after picking up a similar injury in their 2-0 defeat away at Liverpool in mid-April and will now miss their final two league games against Watford and Leicester City.
He is also unavailable for the Europa League semi-final against Eintracht Frankfurt, which is crucial for the club as they aim to qualify for next year's Champions League by winning the tournament, with a place in the top four not yet secured.
Manager Maurizio Sarri will now be forced into another reshuffle, with Christensen set to come back into the starting XI to partner David Luiz.
The Italian coach has no other new injury concerns to worry about ahead of the first leg in Frankfurt on Thursday with only long-term absentee Callum Hudson-Odoi missing.