Toulon and Agen each won in the Top 14 on Sunday, with Racing 92 unable to complete a turnaround while Montpellier were outplayed.
Toulouse won the Top 14 last season but they have been beaten in each of their first two matches at the start of the 2019-20 campaign.
There were shock wins for Bayonne and Bordeaux-Begles as the Top 14 returned for the 2019-20 season on Saturday.
Munster, Racing 92 and the Ospreys will take on holders Saracens in the pool stage of the 2019-20 European Champions Cup.
La Rochelle finished behind Racing 92 in the Top 14 regular season but dumped the Paris club out of the play-offs on Friday.
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.
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.