Racing-Métro became the first team to win in Toulon this season, upsetting the Top 14 leaders 19-15 in a nail-biting encounter at Stade Felix Mayol on Sunday.
The result is Toulon's first loss on home soil since September 2011. RCT nevertheless remain at the summit of the Top 14 standings although their lead over Clermont has been cut to just four points.
Toulon led 9-6 at half time but Racing centre Henry Chavancy's try soon after the interval proved to be the turning point in the game.
Once they had their noses in front, the Parisian visitors produced an immense defensive effort to keep Toulon's star-studded attack at bay and put their mixed start to their season firmly behind them.
Toulon, averaging more than 42 points per game at home and bidding to take their winning streak at Stade Mayol to 19 matches, were outmuscled by a Racing side led magnificently by captain Dimitri Szarzewski and Fiji number eight Sakiusa Matadigo.
After two appearances off the bench since a three-month lay-off following a herniated disc, Racing fly-half Jonathan Wisniewski banged over a seventh minute penalty to open the scores.
But Wisniewski was at fault soon after as he missed a tackle on barging centre Mathieu Bastareaud, Jonny Wilkinson on target with the penalty awarded as Racing hurried to close ranks.
The former England fly-half kicked a second penalty, but Wisniewski drew the score level with a smart drop-goal.
Wilkinson then exited the field after a bloody clash of heads with Benjamin Fall. As "Wilko" was receiving three stitches to the head wound, his Racing counterpart missed a penalty in his absence.
On his return, the Englishman was on hand to hit a third penalty after a stupid offside by Szarzewski to leave the home side 9-6 up at the break.
But the second-half started perfectly for Racing, centre Fabrice Estabanez fending off Bastareaud and Matt Giteau to find Chavency on his inside for a try which Wisniewski converted to open the game up.
Wilkinson fell short with a 52-metre penalty but nailed his next effort to bring Toulon within one point of the Parisians.
Wisniewski stretched the visitors' lead with another penalty and traded a further penalty with Wilkinson in the dying minutes as Racing held out with a formidable defence against an unusually toothless Toulon attack.
"They played great tonight, with a lot of pride," said Toulon captain Joe van Niekerk.
"We're very disappointed. But we'll go away and keep on working. We've lost once here (this season). We're not finished, no way."
Racing now sit eighth in the Top 14 table.
Pens: Wilkinson 5
For Racing Metro:
Pens: Wisniewski 3
Toulon: 15 Alexis Palisson, 14 Delon Armitage, 13 Mathieu Bastareaud, 12 Matt Giteau, 11 David Smith, 10 Jonny Wilkinson, 9 Nicolas Durand, 8 Chris Masoe, 7 Steffon Armitage , 6 Joe van Niekerk, 5 Jocelino Suta, 4 Simon Shaw, 3 Carl Hayman, 2 Sebastien Bruno, 1 Andrew Sheridan, Replacements: 16 Jean charles Orioli, 17 Xavier Chiocci, 18 Nicholas Kennedy, 19 Juan Martin Fernandez Lobbe, 20 Rudi Wulf, 21 Benjamin Lapeyre, 22 Maxime Mermoz, 23 Davit Kubriashvili.
Racing Métro: 15 Juan Martin Hernandez, 14 Benjamin Fall, 13 Henry Chavancy, 12 Fabrice Estebanez, 11 Juan Imhoff, 10 Jonathan Wisniewski, 9 Maxime Machenaud, 8 Masinivanua Matadigo, 7 Alvaro Galindo, 6 Camille Gerondeau, 5 Francois van der Merwe, 4 Manuel Carizza, 3 Luc Ducalcon, 2 Dimitri Szarzewski, 1 Eddy Ben Arous, Replacements: 16 Benjamin Noirot, 17 Julien Brugnaut, 18 Jone Qovu, 19 Antoine Battut, 20 Sebastien Descons, 21 Alexandre Dumoulin, 22 Sereli Bobo, 23 Salemane Sa.
Referee: Pascal Gaüzere