Olivier Klemenczak's last-gasp try snatched a 30-27 victory over Toulouse to move Racing 92 up to third and Castres beat bottom side Agen in the Top 14 on Sunday.
Racing's winning run in the league looked set to end at four matches until Klemenczak nipped in on the blindside to touch down and deny Toulouse with the clock two minutes into the red at Paris La Defense Arena.
Toulouse were pegged back at 17-17 on the stroke of half-time after Dorian Laborde went over, with Fabien Sanconnie also crossing for the capital club either side of scores from Pita Ahki and Lucas Tauzin.
Maxime Machenaud's second penalty of the match put Racing in front, but Sofiane Guitoune finished to put Toulouse ahead again and Cheslin Kolbe took his tally from the tee to 10 points to give them a seven-point advantage.
Racing were not finished yet, though and Teddy Iribaren was on target with a penalty before Klemenczak settled it after Iosefa Tekori was sent to the sin bin with Toulouse under huge pressure right at the end.
Castres are up to 10th after seeing off Agen 43-24, Martin Leveau scoring two of five tries for the 2018 champions.