A 70th minute try from replacement Gavin Hume handed Perpignan a 19-18 victory against Toulouse at the Stade Ernest-Wallon on Friday.
Toulouse fly-half Luke McAlister hit the post with his final penalty attempt in the 75th minute that could have clinched the win, having already landed six penalties throughout the match.
The fixture marked Guy Novès 1000th match with Toulouse as both a player and coach, but his side were unable to honour him with a victory as they remained in second place in the Top 14 following the defeat.
McAlister's kicking accuracy led to an 18-12 lead for the hosts with ten minutes remaining, before Hume struck with the winning try by collecting a grubber kick from David Marty to score, with Wales fly-half James Hook on hand to kick the crucial conversion.
His kick sealed Perpignan's first win away against Toulouse in 31 years, moving them up into 6th place in the table.
Pens: McAlister 6
Pens: Hook 4
Stade Toulousain: 15 Clement Poitrenaud, 14 Maxime Medard, 13 Yann David, 12 Gaël Fickou, 11 Yves Donguy, 10 Luke McAalister , 9 Luke Burgess, 8 Gillian Galan , 7 Gregory Lamboley, 6 Jean Bouilhou, 5 Patricio Albacete, 4 Romain Millo chlusky, 3 Census Johnston, 2 Gary Botha, 1 Gurthro Steenkamp.
Replacements: 16 Christopher-Eric Tolofua, 17 Vasil Kakovin, 18 Edwin Maka, 19 Sylvain Nicolas, 20, Jean Marc Doussain, 21 Lionel Beauxis, 22 Yannick Jauzion, 23 Yohan Montes
USA Perpignan: 15 Joffrey Michel, 14 Farid Sid, 13 David Marty, 12 Lifeimi Mafi, 11 Adrien Plante, 10 James Hook, 9 Florian Cazenave, 8 Henri Tuilagi, 7 Bertrand Guiry, 6 Daniel Leo, 5 Romain Taofifenua, 4 Sebastien Vahaamahina, 3 Kisi Pulu, 2 Guilhem Guirado, 1 Sebastien Taofifenua.
Replacements: 16 Romain Terrain, 17 Sona Taumalolo, 18 Guillaume Vilaceca, 19 Luke Narraway, 20 David Mele, 21 Gavin Hume, 22 Sione Piukala, 23 Jerome Schuster
Referee: P. Gaüzere