Moments after Stephen Myler had been named man of the match, largely for his seven penalty goals, Nick Macleod nicked a losing bonus point for Sale with the last kick of the match. Given that his team had played 20 minutes with 14 men, it was no more than they deserved.
Northampton, however, remain where they want to be, dogging Harlequins and Saracens, confident they can win an away play-off thanks to the power of their set piece. Scrum and line-out served them well enough here, the final indignity being visited upon the Sale pack when they were pushed off their own ball with 10 minutes remaining.
Yet the accuracy required was missing and Northampton seldom threatened the Sale line. The one try went to Mark Cueto after a rare moment of fluidity by Sale backs. They nearly engineered another earlier in the second half, when a neat inside ball by Macleod set Johnny Leota free and Dwayne Peel was held just short.
Northampton were, of course, without their five England players. Jim Mallinder, their director of rugby, believes that Courtney Lawes should be included in England's squad to play Wales next weekend. Lawes came through a second full match showing no sign of the knee injury which removed him from Six Nations consideration, albeit at blindside flanker rather than lock, where England would play him.
But Mallinder needed more from the periods when Andrew Sheridan and Sam Tuitupou were in the sin-bin, one for deliberate offside, the other for a high tackle on Vasily Artemyev.
"We needed to look after the ball better but we had to grind out the victory," Mallinder said, knowing that during the Six Nations, this was Northampton's one home game. Saints have awkward assignments at London Irish and Saracens to come.
Sale recovered well from a 12-3 half-time deficit, when they were fortunate to have collected any points at all. Macleod scuffed his first penalty attempt; in contrast Myler kicked his goals to make the most of a rare start ahead of Ryan Lamb in Northampton's No 10 shirt.
Within 10 minutes of the restart, Sale struck back. Sheridan was still off the field when Myler kicked a fifth penalty but Macleod kicked a second for Sale and Peel orchestrated with Vadim Cobilas the break that led to the try. From the ruck, Rob Miller looped round Peel to give Cueto the score in the corner and reduce Northampton's lead to four points.
Myler kept his side out of range and when he was replaced, Lamb popped over a drop-goal with two minutes left. It stemmed from the only time the Sale line was in danger, Roger Wilson taking an overthrown line-out 20 metres out and Samu Manoa driving to within 10 metres.
Sufficient time was left, however, for Northampton to be offside at a maul. That gave Macleod a chance for a bonus point. From a wide angle, more than 40 metres out, Sale's fly-half kept his club within the mid-table group.
"This was a really good benchmark for us," said Tony Hanks, Sale's head coach. "Not many teams come here and get a losing bonus point. We've come a long way since the start of the season."
The display showed clearly the extent to which this is a season of change for Sale, as they attempt to create unity in a vastly-changed squad. "People who watch us get their entertainment," Hanks said.
Heineken Cup qualification, the main aim, remains well within reach. But Northampton's foundations are stronger, on and off the field.
Northampton Saints P Diggin; V Artemyev, G Pisi, J Downey, N Cato (T May, 78); S Myler (R Lamb, 73), M Roberts; S Tonga'uiha (A Waller, 71), M Haywood (A Long, 58), B Mujati (P Doran-Jones, 61), S Manoa, C Day (M Sorenson, 61), C Lawes, R Wilson, C Clark (capt).
Sale Sharks R Miller; T Brady, J Leota, S Tuitupou (capt); M Cueto (W Addison, 65); N Macleod, D Peel (C Willis, 51); A Sheridan, M Jones (J Ward, 51), T Buckley (Seymour, 52; M Easter, 73), A Ostrikov, J Gaskell, R Vernon, A Powell, D Seymour (V Cobilas, 44).
Referee G Garner (Warwickshire).
Pens: Myler 7
Pens: MacLeod 4