Chelsea captain John Terry is a major doubt for Saturday's trip to Aston Villa despite making a return to training.
Terry missed England's Euro 2012 qualifier against Montenegro on Tuesday with a back problem.
He returned to training on Thursday but may not be risked at Villa Park ahead of next week's Champions League trip to Russia to face Spartak Moscow.
Terry's injury could lead to a recall for fit-again full-back Jose Bosingwa.
The Portugal international has been sidelined with a knee ligament injury for 12 months but has been nursed back to health slowly and is now ready for a first-team comeback.
Bosingwa could return at right-back with Branislav Ivanovic moved to the centre of defence.
"The cruciate is not an easy injury, it's hard to come back at 100 per cent," explained Bosingwa.
"You have in your mind that you can get hurt. It takes a bit of time and you need to be strong to make sure you go into challenges and don't get hurt.
"After that difficulty I felt well and got a few consecutive matches where I was feeling much more confident.
"I don't know what will happen, let's see. I want to keep going as long as I can. I have to work hard and not have any more injury problems, because when you reach an age where you start having injuries it's hard, but you need to play games.
"When you are young if you don't play for a while you are still fresh, but as you get older it's more difficult to come back in."