Montpellier scored to their third consecutive victory against heavyweight opposition on Wednesday, winning 22-21 against Toulouse.
Having toppled title-contenders Racing-Métro and 2009 champions Perpignan in the previous two outings, les Heraultais added the scalp of the current European champions to take the provisional lead in the Top 14 standings.
Toulouse fly-half Nicolas Bezy failed to convert his own try after the final hooter to hand the hosts another upset victory.
Argentina international Martin Bustos Moyano scored all of his team's points: a try, a conversion and five penalties.
Montpellier enjoyed the lion's share of possession and territory in the first half but were unable to seriously threaten the very well-organised Toulouse defence.
The hosts were made to pay for their impatience as the Toulousains profited from a handful of errors to lead 16-9 at the break.
In second half Fabien Galthié's team were more clinical and were rewarded for their enterprise when they ran the ball out of their own half to score a scintillating try.
Bezy put Toulouse 9-3 up on the 25-minute mark with his third penalty after to Montpellier wing Bustos Moyano had opened the scores from the kicking tee.
The Argentine wing reduced the gap to 9-6 after half-an-hour but Toulouse's Fijian wing Vilimoni Delasau ensured the visitors would lead at half-time thanks to an intercept try from deep inside his own half and against the run of play.
Bezy's conversion gave the European champions a ten-point lead, but just before the break, Bustos Moyano smashed a 50m penalty to leave the scores at 16-9 as the teams headed for the changing rooms.
The home side got the second period off to a solid start as Bustos Moyano added his fourth penalty before scoring his side's try, rounding off a flowing move that had started in the Toulouse half.
The Pumas' conversion and another penalty gave Montpol a 22-16 lead going into the final quarter.
Toulouse turned on the tempo in the closing stages but when Bezy missed a relatively easy penalty with five minutes left on the clock, the writing was on the wall for the seventeen-time French champs.
However, in the final minute, from the final scrum of the day, Toulouse spread the ball wide before Bezy switched inside on a sniping run to score.
Try: Bustos Moyano
Con: Bustos Moyano
Pens: Bustos Moyano 5
Tries: Delasau, Bezy
Pens: Bezy 3
Montpellier: 15 Jean-Matthieu Alcalde, 14 Timoci Nagusa, 13 Geoffroy Doumayrou, 12 Santiago Fernandez , 11 Martin Bustos Moyano, 10 François Trinh-Duc, 9 Julien Tomas, 8 Sakiusa Matadigo, 7 Mamuka Gorgodze, 6 Fulgence Ouedraogo, 5 Drickus Hancke, 4 Aliki Fakata, 3 Danie Thiart, 2 Mickael Ladhuie, 1 Sébastien Chobet.
Replacements: 16 Fabien Rofes, 17 Sebastien Petit, 18 Mickaël De Marco, 19 Vassili Bost, 20 Benoît Paillaugue, 21 Sylvain Mirande, 22 Pierre Berard, 23 George Jgenti.
Toulouse: 15 Clement Poitrenaud, 14 Cedric Heymans, 13 Florian Fritz, 12 Yannick Jauzion, 11 Vilimoni Delasau, 10 Nicolas Bezy, 9 Byron Kelleher, 8 Gregory Lamboley, 7 Sylvain Nicolas, 6 Yannick Nyanga, 5 Romain Millo-Chluski, 4 Patricio Albacete, 3 Benoit Lecouls, 2 Virgil Lacombe, 1 Jean-Baptiste Poux.
Replacements: 16 William Servat, 17 Daan Human, 18 Yohan Montes, 19 Thiery Dusautoir, 20 Jean Bouilhou, 21 Jean-Marc Doussain, 22 Vincent Clerc, 23 Maxime Médard.