Saints produced an incredible comeback as they beat Stade Francais 23-22 to secure Champions Cup rugby for next season.
With Rory Hutchinson in the sin bin and Tom Wood sent off, Saints roared back to life and a fantastic try from Ahsee Tuala, allied with a nerveless conversion from Harry Mallinder, earned a wonderful win.
Saints had been up against it from the start and were 22-9 down at half-time as razor-sharp Stade scored three tries.
And although Ben Foden scored to breathe new life into the Northampton bid, things got even harder when Hutchinson was yellow carded for taking Will Genia out in the air.
Saints' hopes looked to have gone up in smoke when England flanker Wood saw red for what was deemed to be a stamp on Stade full-back Djibril Camara.
But Jim Mallinder's men showed remarkable resilience as they had the final say, with Tuala spinning to score in style and Mallinder's kick putting the home side a point up.
Stade couldn't recover and Mallinder missed a penalty with the clock having already hit 80 minutes as the Franklin's Gardens faithful celebrated a vital victory.
Thoughts of a Champions Cup place had looked distant early on as Stade struck in style.
A huge scrum provided the platform for a rapid attack, which saw Camara break through and Waisea Vuidarvuwalu finish.
Jules Plisson easily converted from in front of the posts and he soon added another three points with a penalty.
With just seven minutes gone, Saints had a mountain to climb and the game was being played at a frantic pace.
Stade were looking so dangerous on the counter-attack as Saints poured forward in pursuit of a way back into the game.
Mallinder landed a penalty to at least get the home side on the board, but Stade were a yard quicker and after Genia took a quick tap penalty, Jeremy Sinzelle scored.
It was too easy for the French side to find gaps in the home rearguard, but Plisson did at least provide a little relief as he fluffed the conversion.
Referee John Lacey then infuriated the Saints fans by failing to allow play to go on, whistling for a scrum before Tuala touched the ball down.
Lacey did award a penalty soon after, with Mallinder kicking it to reduce the gap to nine points.
But Louis Picamoles then presented Stade with a big scrum five metres out after knocking the ball on.
And the French team again refused to turn down the opportunity as impressive scrum-half Genia sent Camara through yet another gap to score.
Plisson converted before the Saints supporters booed loudly again as they felt Genia's final pass to the try scorer was forward.
Mallinder missed the chance to respond with a penalty, but he was able to land another opportunity soon after.
And the Saints fly-half made a storming start to the second half, flying forward and leaving the Stade players chasing shadows.
Remi Bonfils felt the need to trip Mallinder and the Stade hooker was yellow carded.
And Saints finally broke the French resistance as Foden flew through a gap and dived over the line in delight.
Mallinder converted to cut the gap to six points, but Stade were still so threatening on the counter-attack, with the speedy Camara leaving several players trailing in his wake.
Herman Meyer Bosman thought he'd scored for Stade, but his effort was ruled out for a forward pass from Camara in the build-up.
Saints could breathe again, but they were to lose a man to the sin bin as, with a penalty coming their way, Rory Hutchinson chased a Mallinder chip and took Genia out in the air.
And it was to get worse moments later as Wood was dismissed, with the TMO deeming the England flanker's boot to have made contact with the head of Camara at a ruck.
Wood was furious with Camara, feeling the full-back had play-acted, and the pair squared up as the home crowd cried 'cheat, cheat, cheat' at the Stade man.
With Hutchinson still in the sin bin, Saints looked like they would now be out of the game. but they stirred in dramatic fashion.
A brilliant long pass from Mallinder set up Tuala and the Samoan full-back spun superbly to see off three defenders and score.
Mallinder held his nerve to convert from out wide and the Gardens erupted in delight as their team took a one-point lead with six minutes to go.
And Stade couldn't recover as Saints fought for every ball, eventually earning a late penalty that saw the clock strike 80.
Mallinder missed the kick but it didn't matter as the Gardens greeted the vital victory with a huge roar.
Saints: Tuala; Foden, Tuitavake (Hutchinson 54), Burrell, North; Mallinder, Groom (Dickson 66); A Waller (Ma'afu 66), Hartley (Haywood 66), Brookes (Denman 61); Lawes, Day (Ratuniyarawa 56); Wood (c), Harrison, Picamoles (Gibson 56).
Stade Français: Camara (Steyn 64); Vuidarvuwalu, Doumayrou, Danty (Bosman 22), Sinzelle; Plisson, Genia (Daguin 76); Zhvania (Slimani 51), Bonfils, Alo Emile, Alberts (De Giovanni 61), Gabrillagues (c), Burban (Parisse 53), Lakafia, Ross.
Referee: John Lacey (Ireland)