Sofiane Guitoune claimed a double as Toulouse beat Grenoble 29-16 to take over as Top 14 leaders, while Toulon snatched victory over Stade Francais in an incredible finish on Sunday.
Clermont Auvergne's defeat at Castres on Saturday gave Toulouse the chance to replace them at the summit and the European Rugby Champions Cup quarter-finalists grasped their opportunity at Stade Ernest-Wallon.
Matthieu Ugalde twice put Grenoble in front from the tee, but Toulouse led 12-6 at the break after a converted Mathis Lebel's score added to Guitoune's opening try.
Ugalde was on target with a third penalty early in the second half before the home side clicked into gear, Guitoune and Clement Castets going over in a decisive six-minute spell.
Zack Holmes converted both scores and was also on target with a penalty, with Mike Tadjer scoring struggling Grenoble's only try right at the end as Toulouse secured a bonus-point win to go two clear at the top.
Toulon looked to be heading for a 10th defeat of a poor Top 14 season before producing a stunning late rally to defeat Stade 33-30 in a thriller.
The three-time European champions came roaring back in the closing stages, Louis Carbonel touching down three minutes from time and Filipo Nakosi scoring his second of a pulsating match at Stade Mayol to leave Heyneke Meyer's men shell-shocked.
Nicolas Sanchez scored 15 points and there was a try in each half for Hendre Stassen, but Stade slumped to a loss which leaves them in sixth spot.
