Top 14 leaders Clermont Auvergne overturned a 19-point deficit on Sunday to claim an impressive win at Bordeaux-Begles and move five points clear of nearest rivals Toulon.
Bordeaux opened up a healthy lead through four first-half penalties from Pierre Bernard, who then converted a 42nd-minute try from Berend Botha.
However, Alifereti Raka and Patricio Fernandez crossed in quick succession to bring Clermont back into the match, following a penalty from the latter.
Clermont's sixth successive victory was then secured by a 70th-minute try from France international Wesley Fofana, leaving Bordeaux stunned.
Toulouse moved level on points with fifth-placed Bordeaux courtesy of a 36-3 thrashing of struggling Stade Francais, but saw Louis Picamoles leave the field through injury.
On his return from a hamstring problem that limited his involvement in the Six Nations, Picamoles was unable to complete the first half.
However, Toulouse nevertheless triumphed comfortably, running in five tries without reply after Morne Steyn had opened the scoring for struggling Stade with a penalty.