Andy Carroll has suffered a fresh injury blow and will miss West Ham's FA Cup fifth-round tie away to Blackburn Rovers on Sunday.
Carroll, who has only recently returned from a hamstring problem, sustained an injury to his adductor in the 2-2 draw with Norwich City last Saturday and will not travel with the rest of the first-team squad to Ewood Park.
The Hammers forward has been blighted by injuries since making the move to the Boleyn Ground in 2012 and spent seven months on the sidelines last year after undergoing major knee ligament surgery.
"It's not a big injury, maybe a couple of weeks," said Bilic. "It happens to him a lot, he can't get a proper routine of games. We are gutted, and he is gutted, at the situation.
"He felt it warming up at Norwich but came on and made a huge impact. Afterwards it turned out to be a minor injury - but still an injury."
Enner Valencia will also miss the trip to Blackburn after suffering an ankle injury at Carrow Road, but midfielder Manuel Lanzini is expected to return following six weeks out with a thigh problem picked up in the 2-0 victory over Liverpool on January 2.