|Northampton (20) 34|
|Tries: North 4 Cons: Myler 4 Pens: Ford 2|
|Ospreys (3) 6|
|Pens: Biggar 2|
Four tries from Wales wing George North saw Northampton reignite their European Rugby Champions Cup campaign by ending Ospreys' unbeaten start to the season.
North crossed twice to help the hosts into a 20-3 half-time lead - although they also had two tries disallowed.
The Saints, stuttered after the break but North powered over for his third try.
And with five minutes remaining he scored a spectacular solo effort to earn Saints a four-try bonus point.
Solid kicking from Stephen Myler did the rest, with Ospreys' points coming from two Dan Biggar penalties.
It was not all good news for Northampton, with England centre Luther Burrell coming off with a hand injury and expected to be sent for an X-ray at the end of the match.
Northampton threw away a losing bonus point last week in the final seconds of their match at Racing Metro, but this win puts them right back in the mix in Pool Five, which also features Italian strugglers Treviso, making it likely that two sides will progress to the last eight from the group.
The Saints' win was built on the power of their pack, with England second row Courtney Lawes having a fine all-round game and United States number eight Samu Manoa putting his considerable frame about to good effect, but it was the devastating finishing power of the 6ft 4in, 17-stone North that put Ospreys to the sword.
With a steady stream of turnovers coming their way, the likes of North, Ken Pisi and Ben Foden enjoyed the chance to pin their ears back, but a stream of errors, including two poor passes from Foden, contributed to the two disallowed tries and a number of other spurned chances.
There was an early exchange of penalties before Saints exploded into life, North going over from Myler's long looping pass to set the hosts on their way.
England squad fly-half Myler then went close himself before Christian Day was denied a try by a Manoa knock-on, but a try seemed inevitable, only for Dylan Hartley to be denied a score by Foden's second forward pass.
The second try finally arrived when North popped up on the right to take a lovely floated inside ball from Pisi and beat two men on his rampage to the line.
Myler converted both scores and any hope the visitors had of getting back into the match were dashed as the normally accurate Biggar missed three out of four penalties either side of the break.
North's power saw him take two defenders over the line to complete his treble and Myler converted, as he would do the final score, but with time fast running out Saints were increasingly worried they were going to miss out on a bonus point.
But North is proving to be a giant not just in stature and he ripped the ball from an opponent on the halfway line with five minutes remaining, kicked ahead and stormed past three would-be defenders to score a stunning try and earn Northampton a precious five-point haul.
Northampton director of rugby Jim Mallinder:
"George is a good player and this was a great performance from him.
"We could have been out of sight at half-time if we'd taken a couple more of those chances we created.
"It usually goes down to the wire in Europe and it will probably be the same this season."
Ospreys forwards coach Chris Gibbes:
"We were inaccurate at times and we allowed them to camp in our half. We knew they were going to be a threat.
"We knew we had to be good from minute one to 80, but we weren't."
Northampton: Foden; K Pisi, Wilson, Burrell, North; Myler, L Dickson; A Waller, Hartley, Ma'afu, Lawes, C Day, Clark, Wood, Manoa.
Replacements: Elliott for Wilson (10), Hooley for Burrell (43), Fotuali'i for L Dickson (58), E Waller for A Waller (74), Haywood for Hartley (63), Denman for Ma'afu (55), Craig for C Day (55), Dowson for Clark (70).
Ospreys: D Evans; Hassler, Bishop, Matavesi, Dirkson; Biggar, Webb; N Smith, Baldwin, Arhip, Peers, A Jones, King, Tipuric, Bearman.
Replacements: Lewis for Webb (73), D Jones for N Smith (63), Parry for Baldwin (67), Jarvis for Arhip (55), Bernardo for Peers (63), Allen for Bearman (39).
Not Used: Roberts, Davies.
Ref: Romain Poite (France).