In-form Montpellier stretched their winning run to eight games with a 26-20 victory at troubled champions Stade Francais to go second in the Top 14 table, while Racing 92 were brought back down to earth by Toulouse on Sunday.
Montpellier secured their place in the semi-finals of the European Challenge Cup with a win over Sale Sharks last time out and maintained their momentum with a triumph at Stade Jean-Bouin to move a point above Toulon and four better off than Racing.
Mickael Ivaldi scored the only try of a tight first half to put the visitors 11-6 up at the break and Akapusi Qera added a second after Jules Plisson's third penalty had reduced the deficit to two points.
Scrum-half Benoit Paillaugue then took centre stage, kicking a penalty and crossing for a try two minutes from time which he converted, with Jeremy Sinzelle's socre coming too late for Stade.
Stade have experienced a huge fall from grace, sitting third-bottom of the table with only seven wins and they were also hammered by Leicester Tigers in the European Champions Cup last weekend.
Racing ended Toulon's European dominance with a dramatic Champions Cup quarter-final win last Sunday, but failed to follow that up in Top 14 as they went down 14-3 at Toulouse.
An under-strength Racing side could only muster an early penalty from Benjamin Dambielle and had Albert Vulivuli sent to the sin bin late in a first half in which all of the points were scored.
Yacouba Camara and Sebastien Bezy scored the only tries of the game to give Toulouse a victory which leaves them seven points behind fourth-placed Racing in fifth spot.