The penultimate round of the Top 14 dished up a couple of upsets as Toulouse and Stade Français lost on the road to Bourgoin and Albi respectively on Saturday while Racing beat Biarritz to secure the final play-off spot.
Racing needed a 79th minute try to sneak past Biarritz, elemintaing the Basques from the play-off race.
Toulouse's chances of hosting a play-off are seriously compromised while Stade Français must now resign themselves to probably missing out on a European place next season.
But the story of the day was Toulon's victory over the title holders Perpignan to take the championship lead for the first time since the creation of Top 14.
Montauban look set for relegation - financial debacles aside - after losing at home to Montpellier.
Bayonne took a big step towards survival and ended Brive's play-off hopes at the same time with a much-needed victory at home.
If - by some miracle - Montauban find the nearly €2m needed to balance their books, their final day tussle with Bayonne will take on epic proportions.
Clermont 25 - 19 Castres
Bourgoin 15-13 Toulouse
Montauban 6-19 Montpellier
Albi 38-24 Stade Français
Bayonne 33-25 Brive
Toulon 33-23 Perpignan
Racing Metro 29-22 Biarritz
1 Toulon 76
2 Perpignan 75
3 Clermont 74
4 Castres 73
5 Toulouse 70
6 Racing-Métro 64
7 Biarritz 58
8 Brive 57
9 Stade Français 53
10 Montpellier 51
11 Bourgoin 49
12 Bayonne 47
13 Montauban 45
14 Albi 24
Clermont Auvergne 25-19 Castres Olympique
Parc des Sports Marcel Michelin, Clermont Ferrand
CS Bourgoin-Jallieu 15-13 Stade Toulousain
Stade Gerland, Lyon
Bourgoin will play in the Top 14 next season thanks to typically courageous battle as they scored their first ever win at Lyon's soccer stadium.
A full-strength Toulouse side came to play, and play they did, scoring the game's only try in the ninth minute when Virgil Lacombe crashed over.
Toulouse led 10-6 at the break but the Heineken Cup semi-finalists fell into the same trap they have far too often this season, trying too much, too soon and their lack of patience cost them dearly.
Argentine full-back Alberto Di Bernardo kicked all five of Bourgoin's penalties, finally giving his side the lead for just seven minutes from full-time.
RC Toulon 33-23 USA Perpignan
Stade Vélodrome, Marseille
What a story it's been for Toulon, who move to the summit of the standings. Le RCT are without doubt serious contenders for the title off the back of yet another convincing display.
Toulon captain Joe Van Niekerk was the inspiration behind a dominant start in a hard-fought tussle as the hosts took the early lead, capitalising on a couple of Catalan errors.
Pierre Mignoni set Luke Rooney up for the game's first try before Perpignan hit back as Farid Sid touched down.
Rooney's second try gave Toulon a 18-13 lead at the break.
Jonny Wilkinson found the mark with a neat drop in the second half to add to his efforts from the tee but a try from Grégory Le Corvec put the defending champions right back into the game.
Wilkinson had the last laugh however, slotting a mammoth drop goal in the dying minutes to deny Perpignan a losing bonus point.
SCA Albi 38-24 Stade Français
Stadium Municipal, Albi
Another failure for Stade Français, who now have no hope of making the play-offs and need a miracle to sneak into Europe through the back door. (They need to finish seventh with a French club winning the tournament).
Victory for Albi means they can leave the Top 14 with their heads held high.
Flanker Antoine Burban and wing Mirco Bergamasco each scored a try for the visitors in the first half but five penalties from Albi full-back Benjamin Lapeyre ensured the hosts led 15-12 at half time.
Second half tries from wing Dave Valinqueur, Kevin Boulogne, Lapeyre gave Albi and incredible 38-12 lead before late touch downs from Lionel Beauxis and Guillaume Bousses gave the Stade scoreline some semblance of respectability.
Montauban 6-19 Montpellier HRC
Stade Sapiac, Montauban
With so much at stake, this was never going to be a high-scoring affair and Sapiac was witness to real arm wrestle.
Five yellow cards were dished out as tempers flared and it took half-an-hour for the first points to be scored. Argentine full-back Fédérico Todeschini gave the visitors a 3-0 half-time lead.
Julien Audy put the hosts a 6-3 ahead with two penalties early in the second half only for Todeschini to level the scores after 50 minutes.
France fly-half Francois Trinh-Duc proved to be the difference between the sides with a drop and then a try in the dying minutes to hand his side victory and assure Montpol of a place in the Top 14 next season.
Aviron Bayonnais 33-25 CA Brive-Corrèze
Stade Jean Dauger, Bayonne
Bayonne climb out of the red zone with one final showdown in Montauban left on the menu.
Brive's hopes of a place in the play-offs evaporated as Bayonne put in one of their best performances of the season, keeping ball in hand and playing some entertaining rugby.
A try form Thibaut Lacroix and Cédric Garcia's boot gave the Basques a 16-0 lead after half-an-hour before Alexis Palisson's penalty left the scores 16-3 at the break.
Brive came back strongly in the second half with Jamie Noon replying to Sam Gerber's try for Bayonne.
Jean-Baptiste Péjoine scored to put the visitors right back in the game but when Ross Filipo crossed for Bayonne with twelve minutes to play, the result looked sealed.
Fabrice Estebanez's late try proved to be too little too late for the Correziens
Racing Metro 29- 22 Biarritz Olympique
Stade Yves Du Manoir - Colombes (Paris)
What a finish! Racing secured the sixth and final play-off berth with a dramatic comeback, snatching victory at the very death.
A Dimitri Yachvili penalty, two drops from Damien Traille and an Iain Balshaw try had Biarritz well ahead before Racing fly-half Jonathan Wisniewski nailed a penalty after the hooter to put the hosts on the scoreboard and leave the scores 14-3.
Racing started the second period strongly as Wisniewski added two more penalties but Aussie import Karmichael Hunt extended Biarritz's lead on 50 minutes to end a counter-attack started by Traille, who was in brilliant form.
Racing continued the fight and when Jonny Leo'o scored in the corner and Andrew Mehrtens slotted the conversion, the hosts were right back in the running.
Yachvili kicked another penalty but Mehrtens then slotted three more to level the scores at 22-22 with twelve minutes left and Balshaw in the sin bin for not releasing the ball when isolated in defence.
The extra man meant it was all Racing in the closing minutes. Sebastien Chabal's charge at the line was finally touched down by Bernard le Roux with the video ref handing Racing the lead for the first in the game in 79th minute!