South Africa have released five players to their French clubs for Top 14 duty this weekend.
Exeter Chiefs will face the Heineken Cup champions for the second successive season after they were drawn with Toulon.
New Zealand winger Hosea Gear will leave the Highlanders at the end of the season to join Top 14 outfit Toulouse.
Toulon remain on course for a Heineken Cup and French league double after beating Toulouse 24-9 in the Top 14 semis.
Heineken Cup champions Toulon will look to close in on the double when they tackle Toulouse in the Top 14 semi-final.
Toulouse booked their place in the Top 14 semi-finals where they will face Toulon after defeating Racing-Metro 33-19.
Toulouse have made the Top 14 semi-finals every year since 1994 but will need to be at their best to beat Racing-Metro.
Toulouse have released former South Africa and Harlequins hooker Gary Botha.
France wing Vincent Clerc has been ruled out for the remainder of the season with a knee injury.
Toulouse have confirmed the signings of Joe Tekori, Jean-Pascal Barraque and Yacouba Camara for the 2013/14 season.
Second takes on third in the pick of the Top 14 fixtures with Clermont set to entertain Toulouse on Saturday.
Luke Burgess is to leave Toulouse at the end of the season, having signed a three-year deal with the Melbourne Rebels.
Racing-Métro secured a crucial result in the race for the Top 14 play-offs with a bonus-point win over Mont-de-Marsan.
Toulouse are without several key players for Friday's Amlin Challenge Cup quarter-final against Perpignan.
Fly-half James Hook kicked 15 points to help Perpignan knock Top 14 rivals Toulouse out of the Amlin Challenge Cup.
A last-gasp try from Vincent Clerc saw Toulouse claim a 27-26 win over Racing Metro, ending the Parisians' winning run.
Luke Burgess looks set to team up with the Rebels after agreeing to an early release from his deal at Toulouse.
Toulon ran in six tries in a comprehensive 50-15 thumping of Biarritz at the Stade Mayol in the Top 14 on Saturday.
Top 14 leaders Toulon host Biarritz this weekend before fourth-placed Castres face the unenviable task of travelling to Clermont.
Clermont notched up a bonus-point win over Stade Francais while Toulon beat Toulouse in Saturday's Top 14 action.