Slaven Bilic says West Ham paid a heavy price for their FA Cup fourth-round replay victory over Liverpool on Tuesday.
Angelo Ogbonna headed the Hammers into the fifth round in the last minute of extra time at Upton Park, but the fixture left West Ham with a lengthy injury list.
Winston Reid and Joey O'Brien were both forced off, Cheikhou Kouyate took a blow to the head, and Enner Valencia looked to pick up a problem after Bilic had used all three of his permitted substitutes.
Michail Antonio and Andy Carroll also appeared to be struggling late on, adding to Bilic's headache as he looks to cope with an already-sizeable list of absentees.
"Unfortunately we had to pay the price with a few of them and we can only hope they won't be out for long," said Bilic.
"Cheikhou felt a little uncoordinated but hopefully he will be okay. Enner looks like a bruise.
"Joey hadn't played for long time so we hope it's just tightness, but with Reid it doesn't look good to me."