West Ham United are waiting on the results of a scan on Diafra Sakho's latest injury after the striker was injured during the 1-1 Premier League draw at Manchester United on Sunday.
It was only the Senegal international's second appearance of the campaign following a long spell out injured, but he could now face another four weeks on the sidelines with a hamstring problem.
With Andy Carroll and Andre Ayew having missed the majority of the campaign and summer signings Simone Zaza, Jonathan Calleri and Ashley Fletcher all misfiring in front of goal, manager Slaven Bilic has another headache ahead of Wednesday's return to Old Trafford in the EFL Cup.
"The scan will show us how bad the injury is," Bilic said. "We don't know yet but he definitely won't play tomorrow. If it's one week, two weeks, four weeks, I don't know.
"It's a big blow for us. He showed against Spurs and against Manchester United what he brings to the team. I can only hope it's not going to be long."
Carroll is on the verge of returning following his latest spell out, having suffered a knee injury in August, but Bilic is weighing up saving the striker's comeback for Saturday's league meeting with Arsenal at the London Stadium.
"We're going to see," added Bilic. "If he progresses like he is with no more things he feels, then definitely for Saturday.
"Maybe tomorrow, but definitely for Saturday. With him it's day by day."
Bilic plans to make changes for the cup clash, with summer signings Sofiane Feghouli and Edimilson Fernandes among those set for a chance.
But the Croatian made it clear he is desperate for the Hammers to get through to the semifinals.
"We are going to do everything we can to beat them," he said. "Man United are probably also going to change their team.
"What we expect is the same shape from them, same kind of football, just different names. When we say we are going to give a few players a chance it doesn't mean we are going just to play a game, and that we regret beating Chelsea in the last round.
"It's a quarterfinal, which means if you win you are in semis and that's a big thing, and only a couple of games to final."