Chelsea captain John Terry could be out for several weeks after aggravating a knee injury ahead of Tuesday's Champions League last-16 first leg match at Napoli.
"John has tried hard to be ready for tonight's game but it was clear after training last night that it was not going to be possible," the club said on their website.
"He will undergo an exploratory arthroscopy in the next day or so after which the club's medical team will be better placed to advise on a prognosis."
Central defender Terry, 31, injured his knee when he collided with the goa-lpost in last month's FA Cup match with second tier Portsmouth.
He has already missed five games and will also be sidelined for next week's England friendly against Netherlands at Wembley.