Stade Francais stunned champions Toulon 30-6 in Paris on Sunday to replace their opponents at the French Top 14 summit.
Paris flanker Antoine Burban (R) fights for the ball with RC Toulon's Mamuka Gorgodze during a French Top 14 rugby match on December 28, 2014 in Paris, France
Tries from captain Sergio Parisse, substitute Jeremy Sinzelle and Georgian prop Zurab Zhavania put the French and European champions, for whom Australia international back James O'Connor didn't come off the bench in what would have been his final appearance before returning home, to the sword at the Jean Bouin stadium.
"I'm proud and satisfied, it's hugely pleasurable to find myself with a group that buys into our project," said Stade's Argentine coach Gonzalo Quesada.
"I'm very happy because we've made massive progress in defence. We won thanks to the attitude we showed in going after the bonus point at the end."
It is six years since Stade have reached the Top 14 play-offs but they will start the New Year in pole position to finally end that sorry record, although they were top three games further into the season a year ago and still missed out.
Stade made a blistering start as the hosts won a scrum against the head in the Toulon 22 and Parisse cantered through a gaping hole to score by the posts after four minutes.
The Parisians had their tails up and were in total control of the early proceedings as fly-half Jules Plisson landed a pair of penalties in quick succession.
The European champions were infringing at the breakdown in an effort to stem the tide of white shirts coming at them and referee Pascal Gauzere's patience finally wore thin as he sent Argentina prop Matias Cortese to the sin bin for a high tackle.
Two minutes later another Toulon forward, flanker Virgile Bruni was also shown a yellow card and with Plisson kicking his third penalty for a 16-0 lead, the writing seemed to be on the wall for the champions.
But playing with a two-man numerical disadvantage focussed Toulon's minds and Argentina fly-half Nicolas Sanchez knocked over a drop goal before Wales full-back Leigh Halfpenny scored a penalty.
Toulon had several chances to close the gap further in the second half but Sanchez hit the bar with a drop goal attempt and put another wide while Halfpenny was well off target with a long-range penalty attempt.
And they paid for it late on as Stade bravely attacked from deep and Geoffrey Doumayrou put Sinzelle over in the corner before Zhvania finished off a sweeping move direct from Toulon's restart.
"It was a difficult night, yes, but we can't accept that," said Toulon backs coach Pierre Mignoni.
"I'll keep to myself what we said to the players. It's not acceptable to play like that."
- Toulouse revenge -
Toulouse gained a measure of revenge on Racing-Metro with a turgid and try-less 15-9 victory.
Toulouse's victory crucially helped erase memories of the record four-time European champions' play-off defeat to the Parisians at their Ernest-Wallon home back in May, denying Toulouse a semi-final place for the first time in 20 years.
Former New Zealand international Luke McAlister scored four penalties with Toby Flood, the ex-England fly-half, adding a fifth for Toulouse, who moved up to sixth in the table and into the final play-off place.
"It wasn't very spectacular but with those conditions we couldn't do any better," said Flood.
Benjamin Dambielle, standing in at fly-half for injured South African Johan Goosen, scored all of Racing's points with two penalties and a drop goal.
Racing remained fourth but missed out on the losing bonus point after opting to kick a penalty to touch late on in an attempt to win the game rather than going for the three points that would have secured the bonus.
"You can see this is a team with a huge amount of pride and desire but they still need more maturity because that kind of point can be important at the end of the season," said Racing coach Laurent Travers.
New Zealander Kendrick Lynn scored a last minute try to give Lyon a stunning 16-13 victory over giants Clermont, who would have gone top with victory.
In other matches, 2013 champions Castres remained bottom despite a much-needed 27-9 win over Montpellier while Bordeaux-Begles ran in seven tries as they thrashed former European champions Brive 46-10.