Leaders Toulon will take on fourth-placed Castres on Friday in the pick of the weekend's Top 14 action.
Stade Francais remain in the Top 14 play-off picture after a backs-to-the-wall victory over Bordeaux.
A 70th-minute try from replacement Gavin Hume handed Perpignan victory against Toulouse at Stade Ernest-Wallon.
The Top 14 action gets underway on Friday when Toulouse look to maintain their impressive home record over Perpignan.
There were plenty of upsets in the Top 14 on Saturday with leaders Toulon thrashed 41-0 by Bordeaux-Begles.
There are plenty of intriguing ties in the Top 14 this weekend, starting with Clermont travelling to Racing on Friday.
Perpignan stayed in the race for the Top 14 play-offs thanks to a hard-fought 26-19 win over high-flying Clermont on Friday.
The dates for the Heineken Cup quarter-finals have been confirmed.
Leicester Tigers clinched the final Heineken Cup quarter-final spot after defeating Toulouse 9-5 at Welford Road.
Stuart Barnes wouldn't be too surprised to see three English sides in the Heineken Cup semi-finals.
A sell-out crowd awaits Leicester for their must-win Heineken Cup fixture with Toulouse at Welford Road on Sunday.
Toulouse and France centre Gael Fickou is ruled out for a month with an ankle injury.
Toulouse recovered from a slow first half to beat Treviso 35-14 to set-up next week's Pool 2 decider against Leicester.
Saracens' humdinger with Racing Metro has ignited this term's Heineken Cup, says Stuart Barnes.
Thierry Dusautoir has been rested for Toulouse's Heineken Cup clash with Treviso on Sunday.
Grenoble claimed yet another big scalp as they maintained their unbeaten home record with victory over Castres.
Top 14 action continues as Toulon look to keep their lead at the summit ahead of the final break before the Heineken Cup Pool run-in.
Clermont closed the gap on Top 14 leaders Toulon on Sunday with a 48-3 win over Bayonne.
Clermont will look to carry their Heineken Cup form across to the Top 14 when they travel to Bordeaux on Friday.
Ulster's home clash with Glasgow will be the first of 11 Heineken Cup round five matches broadcast live on Sky Sports.