Saints saw their 11-match Aviva Premiership winning streak bite the dust in a 19-6 defeat at ruthless Sale Sharks.
Jim Mallinder’s men were toothless in attack, with the Sharks making the most of the opposition’s profligacy to record a win that keeps them in the hunt for a top-four place.
First-half tries from Mark Cueto, Marc Jones and Tom Brady provided a crucial four points for Steve Diamond’s side.
Saints dominated possession throughout, but, despite having all six of their Six Nations stars in their ranks, could not find a way through, with neither side scoring a point during the second half.
Dylan Hartley’s first-half sin-binning was a blow, though Sale were reduced to 14 at the same time, with centre Sam Tuitupou shown yellow for his part in the scrap after the second try.
And with Brady touching down after the incident and fly-half Danny Cipriani pulling the strings, Sale had secured their 10th league win of the season.
For Saints it was another irksome day at the office as they only had two penalties from Will Hooley to show for their efforts.
It was a similar experience to the one at Exeter in the LV= Cup final six days earlier, and, as on that occasion, Saints were hit by the late withdrawal of Stephen Myler.
The first-choice fly-half, who has been struggling with a hamstring injury, was replaced by Hooley, with Glenn Dickson called onto the bench.
And Hooley, the confident 20-year-old, backed himself early on, finding the corner with a grubber kick to put the home side under immediate pressure.
And after Saints won a penalty for Sale failing to release at the breakdown, Hooley stepped up to send his kick through the wind to give his side a 3-0 lead.
Saints had started as they meant to go on, but they were hit with a sucker punch as Dwayne Peel’s scything break carried Sale forward and Cueto dived over in the corner.
Cipriani just about made the conversion, lifting the spirits of the home supporters, who, aside from a continual drum beat, had been largely silent.
Saints returned to the front foot soon after, playing the game in Sale’s half and laying a platform in the forwards, with Dylan Hartley and Courtney Lawes getting involved.
A scrum penalty in front of the posts handed Hooley the chance to cut the gap to a single point, and he did so with aplomb.
Cipriani was less sure at the other end, as his penalty attempt got caught in the wind and drifted wide, quelling the excitement of the hopeful home supporters behind the posts.
But the Sale fly-half was soon booting the ball to the corner as a bad luck struck Saints, with a poor kick through bouncing back into home hands and putting the men in lime under pressure.
The Sharks used their good fortune to great effect, closing in on the line through their driving game, giving hooker Jones the chance to touch down.
Hartley and Tuitupou were binned for fisticuffs after the try was scored, with the long wait hindering Cipriani, who again missed from the tee.
But the enigmatic No.10 was faring better in his management of the game and a perfectly-judged grubber kick sent Brady over in the corner.
Saints had it all to do as Cipriani added insult to injury by finally bisecting the posts with a conversion on the brink of half-time.
Hartley returned to the field soon after the restart, with Saints crying out for some inspiration, having enjoyed little time in the opposition red zone.
The captain helped put the squeeze on with a rolling maul that rumbled towards the home line, but again Sale got off the hook as referee Luke Pearce awarded them a scrum.
The Sharks, though, were shipping plenty of penalties, giving Saints real hope of a revival, but still they couldn’t get over the line.
Hartley, Tom Wood and Jamie Elliott all went within a few yards of a score, but the home defence was proving tough to penetrate.
Time after time, Sale were winning scrums as they held Saints up, refusing to let the men in lime through.
The second half had been a totally one-sided affair, but Northampton were still trying to solve the puzzle of the Sale defence as the final whistle approached.
Meanwhile, the home fans chanted ‘we want four’, urging their side to make the most of one last attack to rack up a bonus-point try.
It wasn’t to come, as Saints were the ones to hold out, bringing an end to a frustrating afternoon in the shadow of the M60.
Sale: Arscott; Brady, Leota, Tuitupou, Cueto; Cipriani, Peel (Cliff 71); Lewis-Roberts (Harrison 65), Jones, Cobillas (Thomas 66); Mills (Ostrikov 48), Paterson, Braid (c), Seymour, Gaskell.
Replacements not used: Croall, Easter, Macleod, Miller.
Saints: Foden; Elliott,Wilson (G Pisi 49), Burrell, North; Hooley, L Dickson (Fotuali’i 49); A Waller, Hartley (c), Ma’afu (Mercey 50); Lawes, C Day, Clark (Dowson 49), Wood, van Velze.
Replacements not used: Haywood, Denman, Craig, G Dickson.
Referee: Luke Pearce