Brendan Rodgers has announced Wesley Fofana will not play again until 2022 after sustaining a medial ligament injury in a pre-season friendly against Villarreal.
Fofana was carried off on a stretcher on Wednesday after a tackle from Fer Nino injured his left leg, with the centre-back later revealing on Instagram he had fractured his fibula.
The France Under-21 international is expected to undergo surgery on Monday, though the extent of the damage is worse than initially feared.
Following Leicester City's 1-0 Community Shield triumph against Manchester City at Wembley Stadium, Rodgers provided a further update on Fofana.
"He has his operation on Monday and he won't play until 2022," the Leicester boss said in his post-match news conference. "At what point that will be we'll have to assess over the next six months or so.
"He's an incredible talent. He's in really good spirits. He'll be back in the training ground on Thursday or Friday next week and will begin his rehab then.”
Fofana became an integral part of Rodgers' team following his arrival from Saint-Etienne.
Out of all Premier League defenders, Fofana was just one of two to attempt at least 50 tackles, complete 50 interceptions and produce 50 headed clearances – Aston Villa's Matt Targett being the other.
"It's such a shame for the Premier League not to have a talent like that and certainly for us as well," Rodgers continued after Kelechi Iheanacho's late penalty had defeated the reigning Premier League champions.
Asked for clarification as to whether the defender had broken his leg, Rodgers responded: "In and around his medial ligament there was a lot more damage than we had hoped, quite substantial damage unfortunately."
While Leicester will be without Fofana for the remainder of the year, they will be buoyed on by the return of Harvey Barnes.
Barnes, who scored nine goals and provided four assists in 25 top-flight fixtures last term, suffered a setback in April with a knee injury ruling him out of the remainder of the season and subsequently contention for England's Euro 2020 squad.
"Unfortunately, I had to watch the amazing scenes [in the FA Cup final]," the 23-year-old told ITV after Saturday's win. "This time, to be on the pitch and be a part of it was amazing.
"I don’t think we approached it as a friendly. It’s a chance to win some more silverware – and something we’ve not won before. We knew it was a great opportunity to win something before the season started, so we’re over the moon with it.
"It’s obviously been a tough few months for me. It’s amazing to be back out there now. This is the first competitive game I’ve played in and for the fans to be back in at Wembley was special. I’m feeling really good and looking forward to the season now."