West Ham could be without influential midfielder Mohamed Diame for up to three months after he tore his hamstring during the Hammers' defeat to Liverpool.
Three former West Ham players - Glen Johnson, Joe Cole and Jonjo Shelvey - all helped sink their former club as Liverpool moved into the top half of the Premier League for the first time this season with a 3-2 victory at Upton Park.
Diame has been a key figure for West Ham this season and after losing striker Andy Carroll to injury last week, manager Sam Allardyce was left ruing his bad luck.
"Not good - it does not take a medical expert to know it is a serious hamstring tear when he falls and stopped the way he did," Allardyce said. "I would expect, in medical terms, for it to be a Grade 3 [injury] and that could be anything up to eight, ten or 12 weeks."
The Hammers, who went behind to Johnson's early strike, recovered well to lead 2-1 after Mark Noble's penalty and an own goal by Steven Gerrard, but appeared to lose their way after Diame was stretchered off in the second half.
"The loss of Diame with a hamstring injury didn't help," Allardyce added. "We lost our forward momentum."