Lyon moved five points clear at the summit of the Top 14 table with a thrilling 25-23 win over second-placed Bordeaux-Begles, while Castres thumped bottom side Stade Francais on Saturday.
The leaders maintained their 100 per cent record and consigned Bordeaux to a first defeat after rolling up their sleeves to come from behind in the second half.
Tries from Romain Buros and Yann Lesgourgues along with 10 points from Ben Botica's boot gave Bordeaux a 20-10 half-time lead.
Lyon rallied after the interval, Jean-Marcellin Buttin scoring his second try of the match before he was sin-binned and Jean-Marc Doussain touching down, then adding the extras to win it after Bordeaux's Jean Baptiste Dubie was shown a yellow card.
Castres piled more pressure on Stade head coach Heyneke Meyer with a resounding 46-16 victory.
There were tries for Thomas Combezou, Jullen Dumora, Geoffrey Palis and Camille Gerondeau as Stade suffered a fifth defeat out of six.
Champions Toulouse slumped to a 23-9 defeat at Brive, with Julien Blanc scoring a try in each half.
Bayonne are up to third following a 29-27 win at Agen, Peyo Muscarditz claiming a quickfire first-half double, while Clermont Auvergne are just a point behind them in fourth after they were 20-13 winners at home to Montpellier.