There will be a new Top 14 champion after Castres missed out on a top-six finish with a final-day defeat to Toulon.
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.
Grenoble look to be heading for a relegation play-off after losing at home to their nearest rivals Agen.
La Rochelle put Pau to the sword and Castres also enhanced their chances of reaching the play-offs with a win in Bordeaux.
Toulon may have been at a numerical disadvantage for most of the second half but they still managed to defeat Top 14 leaders Toulouse.
Tries from Carl Fearns, Mickael Ivaldi and Thibaut Regard helped Lyon get back to winning ways in Saturday's Top 14 action.
There were big wins for 2017-18 Top 14 finalists Castres and Montpellier on Saturday, with Benjamin Urdapilleta inspiring.
Toulouse's lead in the Top 14 table is down to a solitary point after Clermont Auvergne thrashed Grenoble. Lyon, meanwhile, lost at home.
Zack Holmes scored 15 points as Toulouse extended their lead at the Top 14 summit, while Stade Francais boosted their play-off hopes.
Racing 92 ran out of time in their defeat to Toulouse, while La Rochelle survived a Top14 scare against lowly Grenoble.