Monaco's Colombian striker Radamel Falcao requires surgery on the left knee injury picked up in a clash with a school teacher playing for an amateur side in Wednesday's French Cup tie which almost certainly rules the star out of the World Cup.

News of the influential scorer's impending operation was confirmed Thursday in a statement issued by his club.

While Monaco did not specify how long they expected him to be out of action the plight of the nation's top player caused consternation in Colombia.

Images of Falcao, who scored nine goals in Colombia's World Cup qualifiers, with his head in his hands being stretchered off the pitch made the front pages.

Colombia are drawn in Group C at the World Cup with Ivory Coast, Greece and Japan.

France's former national team doctor Jean-Pierre Paclet hinted at a lengthy spell on the sidelines for the 27-year-old who has scored 20 goals in 51 international appearances.

He said: "I don't have his file in front of me but if there's an operation it's because his ligament is ruptured, in the best case scenario it's six months (out) and his World Cup is over."

The Colombian football Federation remained at least superficially calm, with its president Luis Bedoya saying only "let's wait" and reminding Colombian fans that players can be named in World Cup squads "up to the first days of June".

Monaco earlier revealed their record signing had suffered "an anterior cruciate ligament strain" in the 3-0 win at amateur side Chasseley.

It added: "Surgery is required. The doctors will do everything possible to enable Radamel Falcao to recover as quickly as possible."

In Wednesday's ill-fated game, Falcao crumbled to the ground following a challenge and needed lengthy treatment before being carried away on a stretcher just before the interval.

Chasseley disclosed they have received e-mail threats in Spanish, and Soner Ertek, the teacher-cum player whose tackle inadvertently caused the injury, was forced to close his Facebook page after it was targeted with intimidating messages.

The incident has left Ertek distraught.

"I'm overwhelmed by what's happened," he told Lyon daily Le Progres.

"I went to work today because I'm a school teacher and this affair was the only topic being talked about."

He continued: "I repeat again, I'm truly sorry for Monaco, for Falcao, but it's really complicated for me (too).

"From Wednesday I've received requests from 'friends' in Colombia on my Facebook page -- my account has been closed since.

"A fake Twitter account in my name's been opened with all sorts written on it. I want this to stop.

"I'm going to try to contact Falcao via Ludovic Giuly (a former Monaco player who is at Chasseley) to wish him a speedy recovery."

Chasseley's club president Jocelyn Fontanel told AFP there had been no malice in Ertek's tackle.

"There was no aggression," he insisted.

"Accidents happen on the pitch. It wasn't violent ...

"It upset me the whole match, especially as I was beside the Monaco directors.

"Soner didn't do it on purpose, we're not a nasty team. Now there are threats on the internet. I don't know whether we should take them seriously.

"I'm very upset for Falcao."

Falcao joined Monaco for 60 million euros (£50.4m, $82.5m) last summer from Atletico Madrid.

If as looks likely he is robbed of competing at the World Cup Falcao will become the second big name to bow out of Brazil this month after Arsenal's England forward Theo Walcott was sidelined for six months, also with a knee injury.