Monaco midfielder Joao Moutinho will miss up to six weeks with an ankle injury suffered in his side's draw against Lille.
The Portugal international was substituted just after the hour-mark of Monaco's 0-0 Ligue 1 draw at home to Lille on Friday.
Moutinho underwent a series of tests to determine the extent of the knock at the weekend and the club have now confirmed the severity of the injury, saying Moutinho would miss between four and six weeks.
Moutinho's injury is a blow to Monaco's chances of reaching the Champions League group stages.
The 28-year-old is certain to miss his team's playoff against Valencia, who host the first leg on Wednesday.
Monaco are also set to be without Moutinho for their clash against Ligue 1 leaders Paris Saint-Germain on August 30.