Monaco have confirmed that Radamel Falcao faces weeks on the sidelines due to a thigh muscle injury.
The Colombia international was substituted during his side's 3-1 Champions League qualifying win over Fenerbahce on Wednesday, having earlier scored a penalty to help Monaco on their way to a 4-3 aggregate win.
Following tests on the problem, Monaco have announced that they expect to be without the 29-year-old for a number of weeks as he attempts to recuperate.
"Taken off due to injury just before half-time, Radamel Falcao will be absent for several weeks," the club announced via their official website.
"Falcao suffered a muscle injury in his left thigh that will require treatment, a period of rest and recovery over a number of weeks."
Falcao has struggled to maintain fitness ever since he suffered a cruciate ligament injury in January 2014 that ruled him out of the World Cup in Brazil.
He managed just 14 Premier League starts during a loan spell with Manchester United in 2014-15, and he only started twice in all competitions with Chelsea last season, after sustaining a groin injury.