Former New Zealand scrum-half Brad Weber scored twice as Stade Francais held on to beat newly-promoted Vannes 34-31 on Saturday.
Weber, 33, crossed either side of the break as the Parisians won for the first time this campaign having lost at Bordeaux-Begles in their season-opener last weekend.
Vannes, the first club from Britanny to feature in the French top-flight, followed up last Sunday's defeat to champions Toulouse with another loss despite coming within three points of their hosts with a minute to play at Stade Jean Bouin.
Elsewhere, French fly-half Enzo Herve kicked a last-gasp touchline conversion as Toulon edged Castres 30-28.
Later, Stade Francais' local rivals Racing 92 start life without Siya Kolisi as they play Clermont, after the South Africa captain announced his departure last Sunday.
The game has been moved across the French capital to a fourth-tier football ground in the suburb of Creteil.
Racing's usual La Defense Arena home is being re-adapted for rugby after it was used as a swimming venue at the Olympic and Paralympic Games.
Ireland head coach Andy Farrell, who will take charge of the British and Irish Lions next summer in Australia, was expected to be present at the game, watching his son and ex-England captain Owen making his home debut for Racing.
Former Scotland captain Stuart Hogg will miss Montpellier's meeting with Perpignan.
The match comes days after the 32-year-old was arrested and then granted bail for allegedly breaching previous bail conditions ahead of his trial for domestic abuse.
The match will take place 96km east on the Mediterranean coast in Beziers as the pitch at the Catalans' home of Stade Aime-Giral is being re-laid.
The weekend's blockbuster game is La Rochelle's trip to Toulouse on Saturday in a re-run of the 2021 and 2023 finals.
French rugby's poster boy Antoine Dupont remains on holiday and unavailable for Toulouse after clinching gold at the Olympics and rugby sevens.