Chelsea are facing a defensive crisis ahead of their Europa League semi-final first leg at Eintracht Frankfurt.
Maurizio Sarri was already set to be without David Luiz and Antonio Rudiger, who suffered a season-ending knee injury at the weekend.
Gary Cahill has now been ruled out of the trip to Germany after suffering an Achilles injury which could spell the end of his Chelsea career with his contract expiring in the summer.
Full-back Cesar Azpilicueta could feature at centre-back with Andreas Christensen also expected to start - but Sarri admitted they are "in trouble" defensively as they eye a back-door route back into the Champions League by winning the Europa League.
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"Gary Cahill has an Achilles tendon injury," said Sarri. "We hope to recover him in one week.
"So we are in trouble with the centre-backs. For the last two trainings we played with Azpilicueta at centre-back. So we are in trouble.
"We've played 58 matches so injuries are typical. We were lucky previously but not in the last 10 days."
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Chelsea skipper Azpilicueta insisted he is ready to step in at centre-back if required.
"I'm ready to play wherever the manager needs me to play," said Azpilicueta. "But I can adapt to different positions. So I'm ready for it."
Sarri has every confidence in Denmark defender Christensen stepping up at the denouement of Chelsea's quest for Champions League qualification.
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"Christensen during the season has played about 25 matches, so he is ready," said Sarri.
"I hope he will be very fresh, mentally and physically. But I am sure he is ready to play in every match. It's not a problem. The problem is only the number, because we have only two fit centre-backs.
"But I'm really very confident with Andreas because he's ready. He's played very important matches very well, so Christensen is not a problem for us, the problem is the number at the moment."
