Top 14 leaders Racing 92 capitalised on struggling Stade Francais' indiscipline by claiming a 34-16 bonus-point Paris derby victory at Stade Jean-Bouin on Saturday.
Champions Stade have endured a miserable season, but held a 16-13 lead at half-time following a try from Waisea Nayacalevu and 11 points from the boot of Morne Steyn.
Dan Carter converted his own try and added two penalties to ensure there was only three points in at the break. Stade fell apart in the second half to go down to a third consecutive defeat.
Jono Ross and Sylvain Nicolas were sin-binned in quick succession and Mike Phillips soon took advantage of Stade's lack of numbers by going over for a try converted by Johan Goosen to put Racing in front for the first time at 20-16.
Stade's hopes were shattered when they were briefly reduced to 12 men as Sakaria Taulafo was shown a red card for a dangerous tackle on Chris Masoe 13 minutes from time.
Goosen scored a try of his own and added the extras with Carter off the field, then Brice Dulin added insult to injury by claiming the bonus point and Goosen again converted to round off another miserable day for third-bottom Stade.
Racing are now two points clear of Clermont Auvergne, who saw off Brive 25-6, but were unable to claim maximum points.
Isaia Toeava, Alifereti Raka and Peceli Yato crossed in the first half and Morgan Parra helped himself to 10 points from the tee, but there was no further scoring in the second half as Clermont missed out on a bonus point.
Drew Mitchell scored two of Toulon's six tries in a 38-8 rout of Grenoble, which moved the European champions up to third place.
David Smith ran in four of Castres' seven tries in their 50-6 triumph over second-bottom Agen, while fly-half Jean-Pascal Barraque scored two tries and 15 points with the boot in La Rochelle's 35-16 hammering of Pau.