West Ham United skipper Kevin Nolan faces six weeks on the sidelines with a shoulder fracture.
Nolan damaged his shoulder in training on Thursday, missing the Hammers' 3-1 Premier League victory at Crystal Palace on Saturday.
"Kevin fractured his shoulder and that's a massive blow to us, along with all the other players we've got injured," said Allardyce.
"He will be out for probably six weeks I would think.
"It isn't a dislocated shoulder, it's a fractured shoulder, but I don't know just how long that will keep Kevin out.
"We dealt with it brilliantly at Palace and let's hope we can continue to do that.
"It didn't affect us at Palace and maybe that's a sign there's more to come."
For the big stories and the banter follow us on Twitter: @tribalfootball