Everton defender Leighton Baines could be out of action for up to six weeks with a broken toe, the Premier League club announced Tuesday.
The England left-back suffered the injury in last weekend's drawn Merseyside derby, being forced off early in the second half.
An X-ray on his right foot revealed the injury but Everton medical staff cannot, as yet, put a precise timescale on his recovery, with Baines set to be out of action for anything from 10 days up to six weeks.
"It has been confirmed that Leighton has got a fracture in one of the bones in his right foot, which is the phalange," Everton manager Roberto Martinez told the club's website.
"We need to treat that now and see how it develops. It could mean anything from missing six weeks to being back in 10 days because it depends how the fracture heals.
"It is in such a specific spot and we are going to see how it reacts."
Gareth Barry filled in for Baines last weekend, having played at left-back earlier in his career, but Everton would be wary of removing him from central midfield, where he has been a key figure for the Toffees.
"Obviously Gareth slotted in during the game and when you have got a player with that experience, he can play anywhere. I thought he did really well," said Martinez.
"We have got other players at the football club who can play in that position, from Bryan Oviedo to Tony Hibbert and Sylvain Distin to John Stones. We have got many options.
"It's going to be a matter of seeing how the players react in training and, first of all, seeing if Leighton is going to be okay," the Spaniard added.