West Ham have confirmed record signing Andre Ayew is facing four months out with a thigh injury.
The winger - signed from Swansea City for £20.5million this month - had to be replaced in the first half of his debut in Monday's 2-1 Premier League defeat to Chelsea after sustaining the injury.
West Ham had previously revealed that scans had indicated Ayew, 26, would face "a significant rehabilitation period" and co-owner David Gold said on Thursday that the timeframe would be four months, with surgery required to solve the problem.
That would mean Ghana international Ayew is unlikely to feature again for his new club until the busy period of festive fixtures towards the end of 2016.
Gold wrote on Twitter: "Sad news. Ayew has injured his quadriceps and will need surgery.
"He will be out for 4 months. Good luck Andre."
Sad news. Ayew has injured his quadriceps and will need surgery. He will be out for 4 months. Good luck Andre. dg August 18, 2016
