Lyon star Memphis Depay suffered a ruptured anterior cruciate ligament (ACL) in his left knee during Sunday's Ligue 1 loss to Rennes.
Depay, 25, is set to miss the rest of the seasonÂ and becomes a major doubt for Netherlands' Euro 2020 campaign.
The forward has enjoyed a fine Ligue 1 campaign, scoring nine goals and providing two assists in 13 games, but he faces at least six months out of action.
"It's a very bad evening because we lost and because of the lack of quality. The very bad news is also the injury of Memphis, who could be out for a while," Lyon sporting director Juninho said.
"He's our captain and I'm sad for him."
Making matters worse for Lyon, midfielder Jeff Reine-Adelaide suffered a ruptured ACL in his right knee.
Confirming both injuries, Lyon said in a statement the pair were "unfortunately likely to be unavailable for at least six months".
Lyon are eighth in the Ligue 1 table after two defeats in their past three league matches.
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