26 points from the boot of France pivot Frederic Michalak ensured Toulon emerged with a 46-31 victory over Perpignan on Saturday.
The mercurial fly-half kicked six penalties and four conversions as the visitors romped home, securing a bonus point thanks to a second-half Rudi Wulf double, and overtaking Montpellier at the top of the Top 14.
The Heineken Cup champions didn't have it all their own way, however, with relegation-threatened Perpignan giving as good as they got in front of some 25,000 supporters.
Michalak and Wales international James Hook traded penalties early on, before USAP full-back Joffrey Michel crossed for the game's opening try.
Toulon hit back with another Michalak three-pointer, then Virgile Bruni powered his way over to regain the visitors' lead. That was short-lived, however, with Guilhelm Guirado dotting down just before half-time, his try converted by the British and Irish Lion.
But the advantage was with Toulon again at the break, with arguably Europe's form player - Steffon Armitage - scoring a converted try to send Perpignan into the dressing rooms trailing 26-18.
It was largely one-way traffic in the second period, with Michalak adding two more penalties and converting Wulf's double to secure victory for the visitors after Wandie Mjekevu had given Perpignan slim hopes of a comeback.
USAP have now been overtaken by Oyonnax in the Top 14 table, and could drop to 13th if Bayonne beat Grenoble later on Saturday.
Tries: Michel, Guirado, Mjekevu
Cons: Hook 2
Pens: Hook 3
Tries: Bruni, S Armitage, Wulf 2
Cons: Michalak 4
Pens: Michalak 6
USAP: 15 Joffrey Michel, 14 Wandie Mjekevu, 13 David Marty, 12 Lifeimi Mafi, 11 Richard Haughton, 10 James Hook, 9 Dewaldt Duvenage, 8 Daniel Leo, 7 Alasdair Strokosch, 6 Jean-Pierre Perez, 5 Romain Taofifenua, 4 Luke Charteris, 3 Kisi Pulu, 2 Guilhem Guirado, 1 Sona Taumalolo
Replacements: 16 Romain Terrain. 17 Sebastien Taofifenua, 18 Guillaume Vilaceca, 19 Bertrand Guiry, 20 Nicolas Durand, 21 Tommaso Allan, 22 Sione Piukala, 23 Giorgi Jgenti
Toulon: 15 Delon Armitage, 14 David Smith, 13 Maxime Mermoz, 12 Matt Giteau, 11 Rudi Wulf, 10 Frederic Michalak, 9 Michael Claassens, 8 Steffon Armitage, 7 Juan Martin Fernandez Lobbe, 6 Virgile Bruni, 5 Jocelino Suta, 4 Konstantin Mikautadze, 3 Levan Chilachava, 2 Benjamin Noirot,
1 Alexander Menini
Replacements: 16 Jean Charles Orioli, 17 Xavier Chiocci, 18 Pierrick Gunther, 19 Joe Van Niekerk, 20 Mathieu Bastareaud, 21 Drew Mitchell, 22 Sebastien Tillous-Borde, 23 Carl Hayman
Referee: Christophe Berdos