France international Aurélien Rougerie is a major doubt for the World Cup after suffering a horror ankle injury.

The Clermont Auvergne skipper, who has 55 France caps, sustained a fractured and dislocated left ankle while playing for his club against Stade Toulousain on Saturday.

Top 14, r26 Review

The initial damage was done when he was tackled without the ball by Toulouse's Yannick Jauzion in the 33rd minute. Jauzion, who was recently dropped by France, picked up a yellow card for his actions.

Rougerie subsequently aggravated the injury when a team-mate fell on his already damaged ankle.

A Clermont statement after the game confirmed Rougerie had a fracture, as well as damaged ligaments as a result of the dislocation. He will undergo surgery next week and is expected to have a plate inserted.

He will definitely miss Clermont's play-off campaign - they will be at home to Biarritz in the quarter-finals - and must also be a serious doubt for the forthcoming World Cup in New Zealand.

It is a cruel blow indeed for the 30-year-old who led his club Clermont to their first ever Top 14 title last season, and was arguably France's best player during an overall disappointing RBS Six Nations campaign.

France coach Marc Lièvremont had taken to playing Rougerie in the centres this season, moving him in from the wing, and he was a nailed-on certainty for his World Cup squad.

Top 14 League Table 2010/11

Elsewhere, the quarter-final and semi-final fixtures have been confirmed following Saturday's results.

Third-placed Castres are at home - where they have been unbeaten all season - to Montpellier, who pulled off Round 26's most impressive result with a 27-3 demolition of Toulon.

The other quarter-final sees defending champions Clermont Auvergne at home to Biarritz. Clermont, like Castres, have been unbeaten at home all season.

The semi-finals will see Stade Toulousain take on the winner of the Clermont-Biarritz game, while second-placed Racing-Métro 92 face the victors of the Castres-Montpellier clash. Both of the semi-finals will take place at the Stade Vélodrome in Marseille.

Quarter-finals:
Castres v Montpellier
Clermont Auvergne v Biarritz

Semi-finals: (to be played at Stade Vélodrome, Marseille)

Stade Toulousain v winner of Clermont/Biarritz
Racing-Métro 92 v winner of Castres/Montpellier