He will have a scan on Thursday evening after going off at half-time in the Hammers' dismal visit to St. Mary's, and club doctor Ges Steinbergs says: "He has had the groin problem for a while, and has been playing with support, but he couldn't carry on yesterday.
"He will see a specialist and we will see what the situation is from there."
Don Hutchison was also substituted at Southampton - just after being booked - on Wednesday, but Ges says: "He has just a slight calf strain."
Another of the walking wounded is Joe Cole, who limped onto the team coach after the defeat, and Ges adds: "He has a dead leg from a crude challenge."
Meanwhile, Izzie Iriekpen has felt no after effects of playing a full 90 minutes in a friendly at Stevenage on Tuesday.
It was his first full game following a three year knee injury nightmare, and Ges says: "It was nice for him to get involved."