Racing 92 lost 30-25 at home to Vannes on Saturday to extend their record French Top 14 winless run to seven matches.
Ex-England captain Owen Farrell was absent due to injury for the Parisians who are now just two points above the bottom of the table Bretons.
Vannes crossed for three tries in Patrice Collazo's first game in charge of six-time champions Racing after replacing the sacked Stuart Lancaster, the former England head coach.
Racing's capital city neighbours Stade Francais moved above their local rivals to 12th place with a 39-37 win over Pau.
However, the result was clouded for Stade by a serious ankle injury suffered by former New Zealand scrum-half Brad Weber.
Leaders Bordeaux-Begles suffered a second straight defeat, losing 36-32 at Bayonne while Ronan O'Gara's La Rochelle were hammered 53-17 at Lyon.
Second-placed champions Toulouse will be without nine players, including Antoine Dupont, as they have been rested by France during a break week in the Six Nations, when they travel to Clermont on Sunday.