Radamel Falcao will be out several weeks with a thigh injury after being hurt in Monaco's Champions League qualifying tie against Fenerbahce.
The Colombian striker, back in Monaco colours after frustrating loan spells with Manchester United and Chelsea, created Monaco's opening goal and scored their second in a 3-1 win on Tuesday night, helping them through to the play-off round.
But he was forced off at half-time with a muscle injury and on Friday Monaco confirmed that the 30-year-old is set for another spell out.
"Radamel Falcao suffered a muscle injury in his left thigh in the last match which will require treatment, rest and rehabilitation over several weeks,'' the club said on their website.
Monaco paid a club record €60 million to sign Falcao in 2013, but his first season was decimated by a knee ligament injury.
He spent each of the next two seasons on loan in the Premier League, but struggled to make a mark with United and Chelsea as he looked a shadow of his former self.
His preseason form with Monaco this summer had been encouraging prior to this latest setback.