Perpignan suffered a 23rd loss in 25 Top 14 games as Louis Dupichot and Simon Zebo scored hat-tricks in Racing 92's 52-14 victory.
It promises to be an enthralling climax to the battle for Top 14 play-off spots after Stade Francais claimed a derby win over Racing 92.
Top 14 leaders Toulouse enjoyed a fine day as several rivals were beaten amid a series of dramatic finishes.
Sofiane Guitoune's 77th-minute try carried Toulouse past Clermont Auvergne as the top two in the table served up a Sunday treat.
Clermont Auvergne had to settle for a draw against Racing 92, while Lyon held on to beat Pau in a thrilling day of Top 14 action.
Toulouse played almost an hour with 14 men but were still able to beat Racing 92 in a magnificent European Champions Cup quarter-final.
Toulouse are now unbeaten in 14 Top 14 matches after grinding it out at La Rochelle, while Racing 92 got the better of Bordeaux.
There were big wins for 2017-18 Top 14 finalists Castres and Montpellier on Saturday, with Benjamin Urdapilleta inspiring.
Leicester Tigers have confirmed England centre Manu Tuilagi has signed a new deal with the Premiership club.
Kieran Read had been linked with Racing 92 and a Premiership switch, but said it was a "pretty straightforward" decision to move to Japan.