Defending Top 14 champions Toulouse defeated Bordeaux-Begles, who missed the chance to return to the top of the table on Sunday.
Lyon beat Toulon on Saturday to unseat Bordeaux at the summit, and a 22-14 away reverse the following day - inspired by Thomas Ramos - kept the visitors in second.
Ramos scored a try, dispatched two conversions and also a penalty to supply half of Toulouse's points as they climbed to sixth.
There was a dramatic finish at the bottom of the table, meanwhile, as Agen climbed from 14th place thanks to a 23-22 win at Bayonne.
Jamie-Jerry Taulagi bundled his way over in the 78th minute, and Leo Berdeu held his nerve to add the crucial extras in a narrow success.