Leicester boss Brendan Rodgers is expecting Caglar Soyuncu to be out for "a number of weeks" having picked up an abductor strain.
The Foxes' injury concerns ahead of Sunday's Premier League home clash with Aston Villa also include doubts over Jonny Evans and Jamie Vardy.
Rodgers said at his pre-match press conference on Friday: "We think that Cags is definitely out for a number of weeks. The final scans will determine the length of time.
"Jonny has come back with abdominal pain, so again, we'll review that. Vards has an issue around his calf, so we're awaiting a scan on that."
Dennis Praet (knee) is another doubt, and Daniel Amartey (hamstring) is definitely sidelined, but Rodgers has said James Maddison, who missed the 3-0 loss to West Ham on October 4 due to injury, will be available to play some part against Villa.
Soyuncu sustained his injury during the international break while away with Turkey. He did not play in any of the team's three matches.
Evans came off at half-time of Northern Ireland's match against Norway on Wednesday, having played for 210 minutes across games against Austria and Bosnia in the six days before that.
Rodgers said: "Cags – it's unfortunate. For all my time here he has been available, virtually, and he gets injured while he is away.
"Jonny coming back – he's hardly had any pre-season, because of various issues, and now he's had to play nearly three games.
"It's an awful, awful lot of football for players, and they are not machines. Players are exceptionally fit nowadays, but they're not robots."
Soyuncu and Evans' fellow centre-back Wesley Fofana could make his Leicester debut, with Rodgers saying of the 19-year-old Frenchman signed from St Etienne: "I've got no qualms about Wesley coming in to play.
"We've brought him in because he's a big talent but he's ready to come in and play now, even though he's such a young player."
Rodgers also said veteran centre-half Wes Morgan has had "some issues with his lower back, but we're hoping, if he's required, he'll be available to play."
Sunday's match is one of the Premier League fixtures in October not already selected for live coverage that is being made available on a pay-per-view basis, for £14.95 a game.
It was reported Leicester were the only club in 20 to vote against that plan.
And when Rodgers was asked on Friday for his thoughts on the model, he expressed sympathy for the fans.
"I'm disappointed for supporters, because of course at this moment in time it is already very difficult for them," he said.
"If you can't afford to pay that, then you don't get the chance to see the game. I'm hoping it is not going to be for a sustained period of time because it is hurting supporters at the moment not being able to be at the games and the relief they get is through watching it on telly.
"So we wouldn't want to be losing many games to pay-per-view. Let's hope it's not going to be for a long period, and until we get supporters back in, at the very least they get the chance to see it on TV."