Perpignan have booked their place in the Amlin Challenge Cup semi-finals after beating French rivals Toulouse 30-19 at Stade AimÃ© Giral on Friday.
USAP will face either Bath or Stade FranÃ§ais in the last four while Leinster will host Biarritz.
Home tries were scored by Romain Taofifenua, Farid Sid and Sebastien Vahaamahina while Toulouse responded through Edwin Maka.
Toulouse, who had named a largely second-string side, looked to be heading for a half-time lead before Sid crossed in the 37th minute.
And upon the resumption it was all Perpignan as Vahaamahina's try and points from James Hook and Romain Terrain saw them seal their passage into the last four of the competition.
Tries: Taofifenua, Sid, Vahaamahina
Con: Hook 3
Pen: Hook 2, Terrain
Red card: Leo (64 mins)
Pen: Beauxis 4
Perpignan: 15 Gavin Hume, 14 Farid Sid, 13 Lifeimi Mafi, 12 Sione Piukala, 11 Adrien Plante, 10 James Hook, 9 Florian Cazenave, 8 Henry Tuilagi, 7 Alasdair Strokosch, 6 Dan Leo, 5 Romain Taofifenua, 4 Sebastien Vahaamahina, 3 Nicolas Mas, 2 Guilhem Guirado, 1 Sebastien Taofifenua.
Replacements: 16 Romain Terrain, 17 Sona Taumalolo, 18 Kisi Pulu, 19 Guillaume Vilaceca, 20 David Mele, 21 Sofiane Guitoune, 22 Bertrand Guiry, 23 Luke Narraway.
Toulouse: 15 Maxime Medard, 14 Timoci Matanavou, 13 Florian Fritz, 12 GaÃ«l Fickou, 11 Yves Donguy, 10 Lionel Beauxis, 9 Luke Burgess, 8 Gillian Galan, 7 Sylvain Nicolas, 6 GrÃ©gory Lamboley, 5 Edwin Maka, 4 Romain Millo-Chluski, 3 Vasil Kakovin, 2 Jaba Bregvadze, 1 Jean-Baptiste Poux.
Replacements: 16 Christopher Tolofua, 17 Cyril Baille, 18 Yohan Montes, 19 Ruslan Boukerou, 20 Karl Chateau, 21 Yannick Jauzion, 22 Yann David, 23 Sebastien Bezy.
Referee: Alain Rolland (Ireland)
Assistant referees: Greg Garner (England), Luke Pearce (England)