West Ham United summer recruit Andre Ayew could be out for up to four months with the thigh injury he suffered during his side's 2-1 defeat to Chelsea.
Jack Sullivan - the son of Hammers co-owner David - said in a Twitter post that the Ghana international will be sidelined until around mid-December.
"We are devastated that Ayew will be out for about four months. He needs surgery," he wrote.
Ayew, who joined West Ham from Swansea City in a deal worth £20.5m this summer, was thought to be out for only a matter of weeks before a scan revealed the extent of the damage.
