Gabriel Boschilia is set to miss the remainder of the Ligue 1 season after sustaining a serious injury to his right knee in Monaco's victory over Metz on Saturday.
Boschilia twisted awkwardly under a challenge from Jonathan Rivierez in the 66th minute of the 5-0 win at Stade Louis II and was carried off on a stretcher.
Monaco announced on Sunday the Brazilian sprained his knee and ruptured his anterior cruciate ligament.
No official timescale for Boschilia's return has been provided, but it is highly unlikely he will return before the end of the season.
The news will be a blow for the Ligue 1 leaders, who are still competing for silverware on four fronts.