Nuno Espirito Santo revealed that West Ham have suffered a “big blow” on the injury front, with January signing Pablo Felipe sidelined for an extended period.
The Brazilian arrived from Gil Vicente last month for a fee of £20million.
The striker suffered a heavy knock in the 2-0 win over Burnley, and did not recover in time for the visit of Manchester United, where Benjamin Sesko rescued a 1-1 draw for the visitors after Tomas Soucek had opened the scoring.
The Hammers play Burton Albion, the League One outfit, in the FA Cup fourth round on Saturday.
Speaking at his pre-match press conference, Nuno said that Pablo would be out “for a while”.
“He’s injured, unfortunately,” Nuno said. “He’s going to be out for a while.
“We don’t know exactly how long. It’s a big blow for us.
“We don’t know, we’ll have to assess it day by day.”
The Irons boss hinted that he could also rotate his starting lineup for the trip to Staffordshire.
“The cup is a good chance for players that are not ahving too many minutes to have a chance to play and improve.
“You’re going to need them further ahead. It’s an important competition for us, that we respect. We’re going to try and go through, and see where the FA Cup leads us.”
Nuno confirmed that the rest of his squad - barring Jean-Clair Todibo, who remains suspended after his red card at Chelsea - would be available for the cup tie.
The east London club next face Bournemouth in the Premier League, as they sit three points off safety.
