Radamel Falcao is in danger of missing the World Cup following confirmation he will need surgery after suffering anterior cruciate ligament damage.
The prolific Colombia international sustained the injury during Monaco's Coupe de France tie against Monts Or Azergues on Wednesday night and he underwent tests on Thursday.
The results of those tests have confirmed the extent of the damage to his left knee and Monaco have announced that Falcao will now need an operation
Monaco have not said how long Falcao is likely to be absent for, only that doctors would try to help the striker recover as quickly as possible.
However, there must be real concern now for Falcao and Colombia that he will be ruled out of this summer's World Cup finals in Brazil, with recovery time for a serious ACL injury typically between six and nine months.
A club statement on asm-fc.com read: "Following the injury suffered on Wednesday, Radamel Falcao has had medical tests. It appears that the player has a lesion of the anterior cruciate ligament in his left knee.
"An operation will be necessary in the coming days. The doctors will therefore make every effort to allow Radamel Falcao to recover as quickly as possible."
Falcao later wrote on Twitter: "I want to thank all of you for so many messages of support in the last few hours, I'm really touched by the warmth that's been shown to me from all over the world.
"I'm not going to deny that my sadness is huge, my heart is broken, but I'm clinging to the smallest hope, and that's enough to think that my World Cup dream is still alive.
"God makes possible the improbable, I believe in Him!!!"