Racing 92 fought back from 11 points down in the second half to seal a thrilling 39-35 win at Grenoble and go five points clear at the top of the Top 14 standings.
It looked as though the visitors were set for a comfortable win when they went 21-9 up inside half an hour, only for Grenoble to fight back strongly and forge into a significant lead of their own.
Antonie Claassen, Teddy Thomas and Juan Imhoff had all crossed for Racing, but Grenoble went into the break 26-21 to the good thanks to quickfire scores from Loick Jammes and James Percival, combined with the boot of Jonathan Wisniewski.
In the second period, three more Wisniewski penalties - taking his season tally to 25 - had Grenoble 35-24 in front with 13 minutes remaining.
However, Xavier Chauveau's try reduced the arrears for Racing, before Carter's quickly-taken kick to the corner caught out the Grenoble defence and Joe Rokocoko gathered to score, Carter adding a penalty with the final action of a thrilling encounter.
The bonus-point win kept Racing top and meant they surged clear as nearest rivals Toulouse lost 28-8 against La Rochelle in the day's late game, with Zack Holmes' 23-point haul with the boot proving the difference.
In third place are Clermont, who defeated Castres 28-17 away from home while elsewhere, Bordeaux-Begles overcame bottom side Agen 24-19, and Pau staged a dramatic late comeback, scoring 10 points in the final 10 minutes to defeat Montpellier 19-16.