West Ham goalkeeper Adrian is set to miss the last three games of the season after injuring a calf muscle during last weekend's 3-0 win at West Brom.
Adrian, 29, has only missed three games for the Hammers this season but will sit out Saturday's visit of Swansea.
"It's minor but unfortunately because it's his calf he is probably out for the rest of the season," said West Ham boss Slaven Bilic.
Republic of Ireland keeper Darren Randolph will step in.
"We have a great deputy," said Bilic. "Whenever he has stepped in, he's been brilliant.
"He's one of the reasons we went far in the FA Cup. He was great against Manchester United, home and away, and Liverpool. We're happy to have him."
West Ham are sixth in the Premier League, five points behind fourth-placed Manchester City with a game in hand, as they chase a spot in the Champions League.
The Hammers are one point behind Manchester United, who are fifth, with both teams having three games to play.