Bordeaux - Stade Francais stunned triple European champions Toulon 33-16 on Friday to reach the French Top 14 final.
Led by the irrepressible Italian back row forward Sergio Parisse, Stade scored tries through flanks Raphael Lakafia and Antoine Bourban, before a freak late score from wing Julien Arias gave a flattering skew to the final score as they reached their first final since defeating Clermont 23-18 in 2007.
They could meet Clermont again in this year's final if the former get past Toulouse in Saturday's second semi-final.
"There's a lot of joy, I still can't believe I'm here talking about this match that we've won," admitted Lakafia.
"I've no preference between Clermont and Toulouse, may the best win, as long as we're champions at the end!"
Toulon had opened the scoring through Australian wing Drew Mitchell but then paid for crucial handling errors and numerous turnovers as Stade beat them for the third time this season.
It was a sad end for a number of veteran stalwarts whose club careers ended with this defeat, including South Africa's Bakkies Botha, Ali Williams and Carl Hayman of New Zealand.
"We were weak, with three or four players who didn't perform but despite that we should have scored at the end of the first half," complained Toulon's outgoing head coach Bernard Laporte.
"Instead we conceded a try under the posts and that killed us."
Toulon paid tribute to Jerry Collins, the former All Black who dies in a car crash on Thursday, wearing black armbands while No 8 Chris Masoe bleached his hair in homage to his fallen friend.
The champions may have topped the regular season standings, as they did last year before winning their first title in 22 years, but Stade had the Indian sign on them during their league meetings.
And Gonzalo Quesada's team did it again with a spirited display in Bordeaux.
If Stade's task in upsetting the treble European champions wasn't already hard enough, they gifted the reigning French title-holders an early try as well.
Juan-Martin Hernandez chipped ahead down the right wing and Stade backs Jonathan Danty and Djibril Camara collided in trying to recover the bouncing ball, allowing Mitchell to snatch it out of the air and run unopposed to touch down.
Wales international full-back Leigh Halfpenny added the extras and six minutes in, Stade's mountain appeared even more imposing than ever.
Yet the Parisians quickly regrouped and South Africa fly-half Morne Steyn kicked a penalty to get them off the mark.
Halfpenny responded on 11 minutes only for Steyn to land a monster of a kick from halfway to cut the deficit to 10-6.
The game swung on a moment of genius from inspirational captain Parisse on 24 minutes, clawing a looped pass from prop Rabah Slimani out of the air one-handed and then playing a pass behind the back inside, taking out two tacklers, for Lakafia to dive over.
Steyn made no mistake with the conversion and for the first time Stade were in front.
Halfpenny missed a penalty five minutes later but did draw Toulon level on 33 minutes.
Yet there was still time for Stade to take charge before the break following a fluid period of running rugby in which the ball changed hands several times from turnovers.
Toulon failed to secure the ball at the back of a ruck close to halfway and Bourban pounced.
Picking up the loose ball he was surrounded only by Toulon front rowers and easily weaved through a gap before sprinting in for the score, which Steyn converted for a 20-13 halftime lead.
Halfpenny and Steyn again exchanged penalties early in the second half, although the Springbok international also dropped another long-range effort inches short of the bar.
Steyn kept trying the long distance kicks from ever further away but from inside his own half he couldn't find the distance.
Yet he did notch a kick from much closer in after Toulon flanker Steffon Armitage held on in the tackle to give the Parisians a 10-point lead with less than 10 minutes remaining.
Toulon twice fumbled the ball in the Stade 22 when pushing for a try and then did so again after the final buzzer when trying to run back the ball from behind their own tryline, gifting Arias an easy score.