Niclas Fullkrug is set for an extended spell on the sidelines, in a huge injury blow for new West Ham manager Graham Potter.
The 31-year-old against Aston Villa on Friday pulled up with a hamstring issue and quickly signalled to the bench before collapsing to the pitch.
Crysencio Summerville also picked up an injury in the FA Cup third-round clash, but West Ham are hopeful the winger’s fitness woes are less severe.
Fullkrug was helped from the pitch by medical staff as West Ham lost 2-1 at Villa Park in Potter's first game in charge.
Potter confirmed after the game that Fullkrug's injury appeared serious and West Ham have now confirmed the striker faces “a number of weeks” out.
Reports earlier on Sunday suggested Fullkrug could be sidelined for up to three months.
It is another huge blow to both club and player, with Fullkrug having already missed three months of his debut season with an Achilles injury.
The Germany international has made just three Premier League starts since arriving from Borussia Dortmund in a deal worth £27million.
