Monaco's Colombia striker Radamel Falcao faces an anxious wait to find out if he has a serious knee injury after being taken off on a stretcher in the French Cup on Wednesday.

Falcao opened the scoring for Monaco in the 29th minute with his 11th goal of the season, but was caught by a heavy tackle from Chasselay center half Soner Ertek in the 40th as he charged into the penalty area. Falcao, tipped to be a star at the World Cup, was clearly in pain as he clutched his left knee and immediately called for medical attention.

After receiving treatment he was stretchered off a few minutes later and replaced by Emmanuel Riviere, who scored twice in the second half as Monaco won 3-0 to reach the last 16.

Sweating: Monaco face an anxious wait to discover the extent of a knee injury suffered by star striker Radamel Falcao

Totally Rad! Falcao became the Ligue 1 club's marquee signing when he joined from Atletico Madrid for £49m last summer

Flashpoint: Falcao is brought down by Chasselay center half Soner Ertek in the penalty area, but no foul was awarded

Chelsea and Real madrid have been long-term admirers of Falcao but  any move looks likely to be put on hold, while the injury could also jeopardise Stoke's hopes of signing Riviere.

Monaco have released the statement: 'Falcao was hit in the left knee. We must wait for further tests in the coming days to clarify the nature of the injury.'

The 27-year-old Falcao turned neatly into the area as he received a pass and, as he was about to line up a shot, Ertek came charging in from the side and all of his weight hit Falcao's knee. Remarkably, no penalty was given, even though Ertek was nowhere near to getting the ball.

Monaco coach Claudio Ranieri was furious with match referee Philippe Kalt for not taking firmer action against Chasselay's players. As Falcao was being taken away, Ranieri remonstrated furiously with Kalt, and could be heard screaming 'I told you before.'

After the game, Ranieri explained that he felt his players had not been protected enough.

'I'm very satisfied (with the result), but I'm not happy with the referee,' Ranieri said. 'It's normal that the Chasselay players were tough, and that something could happen to someone. But there were no cards given. I hope that it's nothing serious for Falcao.'

'If Falcao has a serious injury, it's the referee's fault. It's not possible to let things go like that," Ranieri added.

'When there are fouls, you have to whistle. When it's a bad foul, you have to get a yellow card out and if there's another bad foul, then it's a red. Tonight I saw neither.'

Nasty! Falcao is carried off on a stretcher during Monaco's 3-0 win against Chasselay in the French Cup

First blood: Falcao (C) is congratulated after opening the scoring against the amateur side

Fuming: Monaco coach Claudio Ranieri was furious with the tackle, claiming the referee should have after offered his layers more protection

Midfielder Jeremy Toulalan fears that Falcao's injury could be bad.

'We've lost Radamel. It's a big blow for the future,' Toulalan said on French television. "I think it's serious. The news isn't reassuring."

Falcao is Colombia's key player and he has scored 20 goals in 51 international matches for Colombia, which has qualified for this year's World Cup in Brazil.