Arsenal defender Laurent Koscielny has ruptured his Achilles and will not play again "before December", according to departing Gunners boss Arsene Wenger.
The France international sustained the injury in the early stages of their Europa League semi-final second leg against Atletico Madrid at the Wanda Metropolitano and his country's football federation confirmed on Friday he will miss the World Cup.
And Wenger fears the 32-year-old will miss the first three months of next season as well.
Speaking ahead of Wednesday's trip to Leicester City, he told a news conference: "He is devastated because he has surgery that means six months out. You will not see him again before December certainly."
Asked if Koscielny was struggling to cope with the enormity of missing the World Cup, due to be his final international tournament after already announcing he was going to retire from Les Bleus duty following Russia 2018, Wenger added: "We always try to be positive, you know, but overall you can only try to support people when they suffer, because they do suffer from a situation like this.
"What is unusual in this case is that he had tendonitis for a while and it doesn't usually go to a rupture. That is a bit surprising in this case. When inflamed it doesn't always go to rupture, but it did – I don't know why."
Speaking on Friday, France boss Didier Deschamps admitted Koscielny's absence is a major setback for the 1998 champions.
Deschamps said: "It's a very big blow for the French team. An injury never comes at the right time.
"I am really very sad for Laurent because this World Cup was also a very important moment for him in his career and I wish him strength and a good return to the field because I'm sure he still has some great things to show."
Wenger's final game with Arsenal after 22 years in charge is Sunday's trip to Huddersfield Town.
Speculation continues as to his successor with Luis Enrique, Mikel Arteta and Massimiliano Allegri reportedly the leading candidates.