Ayew was replaced 30 minutes into West Ham's 2-1 defeat by London rivals Chelsea on Monday
West Ham United's record signing Andre Ayew faces four months on the sidelines after injuring his thigh on his debut, club co-owner David Gold said on Thursday.
Ayew was replaced 30 minutes into West Ham's 2-1 defeat by London rivals Chelsea on Monday, and Slaven Bilic's side are now likely to be without their high-profile recruit until the New Year.
"Sad news," Gold wrote on his official Twitter handle. (@davidgold) "Ayew has injured his quadriceps and will need surgery.
"He will be out for four months. Good luck Andre."
The Ghana international joined for a club record fee of 20.5 million pounds ($26.71 million) from Swansea City earlier this month, having scored 12 goals in 34 Premier League outings last season.
Stijn Vandenbroucke, the club's head of medical and sports science, told West Ham's website on Wednesday that the forward faced a "significant rehabilitation period."
West Ham, who finished seventh last season, will play their first league game at their new London Stadium home on Sunday when they host Bournemouth.