Everton boss David Moyes has revealed Darron Gibson is playing through the pain barrier.
The former Manchester United man has a build-up of calcium at the top of his thigh.
Moyes said: "I think we are in control of Gibson but there is a danger.
"We thought he might need an operation earlier in the year but the medical staff have managed it well. We think we can get away with it just now but he will need an operation."
Moyes added: "I don't question his character as he came from a club that instils that in you.
"We're not going to let him roll over so we can tickle his belly.
"He's going to have to get up and get on with it - and he has done, to be fair."