A last-minute penalty from Fabien Fortassin saw Montauban to a surprise 18-16 win over Top 14 title-challenging Clermont.

Mirko Lozupone's 63rd-minute try looked to have given the leaders the victory, but Fortassin stepped up to steal the points for the home side.

The Montauban fly-half scored all 18 points for his side, while opposite number Seremaia Bai ended with 11 points.

Stade Francais beat Castres 44-15 in Paris to earn their place in the last-four.

Boela Du Plooy scored twice, while Julien Saubade and Mirco Bergamasco also scored as the home side dominated the second half with a late surge.

Clermont, Toulouse and Stade Francais already have their last four berths and now it is down to Perpignan and Biarritz for who gets the last slot.

Biarritz are still clinging on to their hopes of nicking fourth place from Perpignan after beating Bourgoin 30-10 at home.

Captain Imanol Harinordoquy scored the home side's fourth try in the 80th minute to secure the win and the bonus point hat comfirms their Heineken Cup place for next season.

Perennial strugglers Dax lost their fight to stay in the top flight after they lost at home 16-36 to Montpellier, while Albi won their largely meaningless mid-table match with Bayonne 13-6.

Eurosport