Republic of Ireland striker Sammie Szmodics requires ankle surgery and will be ruled out until the closing weeks of the Premier League season.
The Ipswich Town man will miss Ireland's upcoming UEFA Nations League play-off matches with Bulgaria and some crucial games with his club.
Heimir Hallgrímsson names his squad next week, with attacking options depleted as fellow Ipswich man Chiedozie Ogbene is also out injured.
Town boss Kieran McKenna, whose side will bid for just their fourth league win of the season on Saturday at Crystal Palace, said: "Sam Szmodics has gone for an ankle operation, unfortunately.
"So he’s going to be out for an extended period of time. He originally suffered the injury in a tackle in the Fulham game, then had a recurrence of it in the Coventry game, then he had a recurrence of it after the Manchester United game.
"I don’t know the exact timescale, but it’s going to be a good number of weeks and if we see him again this season it will be in the last couple of fixtures."
The Tractor Boys' Premier League survival battle is being undermined by injuries and the crisis shows no sign of easing, with defenders Axel Tuanzebe and Cameron Burgess also added to a lengthy list of absentees.
McKenna was without eight first-team players for Monday’s FA Cup penalty shoot-out defeat at Nottingham Forest, while Tuanzebe (hamstring) and Burgess (calf) were both forced off at half-time.
"In terms of those who went off the pitch, Axel won’t be available for this weekend and Cameron Burgess is still being assessed," McKenna added.
"We have one or two who may be able to rejoin the squad who weren’t involved on Monday night, and we’ll have one or two who were there on Monday night who won’t be available. And we’ve got a few who will be assessed (on Friday).
"It’s certainly a bit of a tricky period for us at the moment. We’re trying to make the right decisions and get a competitive squad available for Saturday."
Julio Enciso and Omari Hutchinson (both knee) are edging closer to full fitness and McKenna must decide whether to risk including them in his squad for the game at Selhurst Park.
Ipswich, five points from safety in 18th place, are winless in their last eight league games and bidding to secure their first victory since beating Chelsea at home in December.
