Lyon midfielder Yoann Gourcuff is set for up to three months on the sidelines after picking up a knee injury in the win over Troyes.
The Ligue 1 club have confirmed that the France international damaged his medial ligament in the early stages of Saturday's 4-1 victory and now faces at least six weeks out of action.
A statement on Lyon's official website read: "Yoann Gourcuff underwent an MRI on Monday morning which revealed a sprained right knee with an injury to his medial collateral ligament.
"He is expected to spend between six weeks and three months out, depending on how the injury responds."
The 26-year-old scored the only goal in Lyon's 1-0 win over Rennes on the opening weekend of the season but has been plagued by injury in recent seasons.