Saints produced a sensational Champions Cup performance as they scored five tries in a 34-21 victory against Clermont Auvergne.
The French giants had headed to Franklin's Gardens with a 100 per cent record in Pool 2, but they were met with a ferocious display from the home side.
Each one of Saints' scores was worthy of acclaim, with Teimana Harrison, Nafi Tuitavake, Ben Foden, Ken Pisi and Cobus Reinach the men on the mark.
Harry Mallinder, playing at fly-half, kicked nine points to add gloss to the scoreline as the green, black and gold continued their 100 per cent start to 2018.
The arrival of coaching consultant Alan Gaffney has helped to galvanise a squad that had previously suffered four defeats from as many Champions Cup pool matches.
They had shipped a try bonus point in each of those losses, but this time it was Saints who were doing the damage.
They showed incredible amounts of spirit, especially after going behind early on when Clermont wing Remi Grosso used his power to score in the corner.
Morgan Parra placed the ball between the posts to add the conversion, but Saints refused to buckle, battling for every loose ball as they sought a way back into the game.
And they were to get it as Api Ratuniyarawa brilliantly blasted holes in the Clermont defence before offloading and eventually the pass was flung wide to No.8 Harrison for the score.
Mallinder missed both conversion attempts, retaking it after Clermont shouted during the first effort, but Saints had narrowed the gap to two points.
It didn't take long for the French side to restore their seven-point advantage though as a slick move finished with full-back Isaiah Toeava diving over.
But the Saints fans were furious with referee George Clancy for refusing to penalise Clermont for what they felt was a forward pass in the build-up.
Clancy claimed to be satisfied that Nick Abendanon had not sent it forward and the home players and supporters were incensed.
Parra missed the quickly-taken conversion to turn the loud boos to cheers, and he was off target again soon after, missing a penalty after Courtney Lawes was penalised.
It was turning into a penalty-fest for Saints, who were being penalised at every turn and after they were punished for collapsing the scrum, Parra rediscovered his kicking boots.
But Clermont were soon hit with a sucker punch as Tongan centre Tuitavake, a HIA replacement for Ahsee Tuala, gathered a Foden kick and slalomed his way over the line.
It was a fine finish but not matched by the conversion attempt as Mallinder missed a kick he would expect to make.
That left Saints five points behind at the break, but they were on the front foot from the off at the start of the second half and Mallinder made amends by landing a penalty.
But the best was yet to come as Foden gathered the ball inside his own half, spotted a gap and left Clermont bamboozled as he sprinted over the line to score a superb try.
Mallinder kicked the conversion brilliantly from the touchline and his team had a five-point lead with 35 minutes to go.
Parra quickly cut the gap to two with a penalty and he put his team back in front with another effort after Campese Ma'afu was penalised at the scrum.
Saints refused to relent though and with a penalty coming, Mallinder sent a crossfield kick towards Rob Horne, who contested well and knocked the ball down for Pisi to pounce.
The Samoan's effort bagged the bonus point for Saints and Mallinder superbly slotted the conversion to make it 27-21 with 15 minutes to go.
It was to get even better nine minutes later as a patient team move, packed with fire and desire, resulted in replacement scrum-half Reinach scoring in the corner.
Mallinder again converted from the touchline, drawing yet more cheers from the home supporters who had been on their feet in delight after the fifth try was scored.
And the roar was even louder when referee Clancy called an end to the game, confirming a special win for the Saints.
Saints: Tuala (Tuitavake 29); Pisi, Horne, Stephenson, Foden; Mallinder, Groom (Reinach 60); Ma'afu (Van Wyk 62), Hartley (c) (Haywood 62), Brookes (Ford-Robinson 75); Ratuniyarawa (Paterson 75), Day; Lawes, Wood, Harrison.
Clermont Auvergne: Toeava; Abendanon, Betham, Lamerat, Grosso; McAlister (Spedding 65), Parra (c); Falgoux (Chaume 65), Kayser, Slimani (Zirakashvili 64); van der Merwe (Iturria 54 (Jedrasiak 69)), Vahaamahina; Chouly, Lapandry, Lee.
Referee: George Clancy (Ireland)