Saints completed their Italian job before needing to call on their star-studded bench as a bonus-point was claimed in a fine 38-15 Champions Cup win at Treviso.
Scores from Samu Manoa, Alex Waller, Ben Foden and Luther Burrell ensured Jim Mallinder’s were home and dry before introducing some of their biggest names.
A penalty try and an effort from Samoan centre George Pisi on his return from injury put the gloss on a fine performance.
Mallinder had seen Dylan Hartley, Courtney Lawes and Tom Wood return from international duty earlier in the week, but chose to leave the England men on the bench.
Instead, he kept faith with the majority of the side that had served him so well during the autumn internationals - and his decision paid dividends.
The first replacement was not made until birthday boy Burrell had dotted down for the fourth try 10 minutes after the break.
And although Treviso grabbed two consolation scores, through Ludovico Nitoglia and Joe Carlisle, it was a job well done for Saints, who finished with a flourish.
The win means they remain in contention at the top of Pool 5, with 10 points from three games and welcome Treviso to Franklin’s Gardens next Saturday.
The characterful Stade di Monigo had felt a little like the Gardens, such was the backing the travelling army of supporters provided.
With strains of “Oh When the Saints” ringing around the ground, Mallinder’s men started brightly, with fired-up Phil Dowson winning an early penalty at the breakdown.
It was to be a theme of the formative stages of the match as Saints squeezed penalty after penalty out of their hosts, continually putting the pressure on from the lineout.
It looked merely a matter of time before they made the possession pay, and it was American behemoth Manoa who used his muscle to claim the first try of the game.
Stephen Myler landed the conversion with aplomb, to the delight of the army of away fans, who continued to lift the noise levels.
Tom Stephenson was roared on as he looked to charge clear, but the persistence of Michele Campagnaro paid off as he eventually stopped the Saints centre on the 22.
Treviso were content to continually kick the ball into Saints territory and it paid dividends on 20 minutes as the away side failed to gather and were quickly penalised.
Fly-half Carlisle fizzed the penalty attempt between the uprights from distance to get his side on the board.
Myler had the chance to restore his side’s seven-point lead at the other end, but fired his effort to the right of the posts.
It was turning into a turgid encounter, with the home side doing little to entertain their success-starved fans.
And Saints were soon celebrating a second score as more relentless forward pressure forced Antonio Pavanello into offending and being sent to the sin bin before Waller scored.
Myler’s conversion rebounded off the left post before Saints defended stoically at the other end, shoving a Treviso maul back and turning the ball over superbly.
The home side did get a chance to narrow the deficit before the break, but Carlisle’s kick was struck poorly and fell well short of the posts as the half-time whistle sounded.
Saints were soon on the front foot at the start of the second period and after pressure again built in the Treviso 22, a clever offload from Burrell teed up Foden for another score.
Myler’s kick was perfect and barely had Treviso kicked off than Saints were crossing for the bonus-point try.
It was a superbly worked effort, started by a blistering burst from Jamie Elliott and finished by Burrell.
Myler again made the conversion look easy and Saints had a 26-3 lead as well as an extra point in their suitcases.
Treviso’s misery was compunded by the sight of some of Saints’ replacements being thrown into the action, with Kahn Fotuali’i and Wood among them.
George Pisi was also brought into the action, making his first appearance since injuring his hamstring in the Champions Cup opener at Racing Metro in October.
But the raft of changes disrupted Saints a little and Treviso had some hope of a comeback when wing Nitoglia dotted down in the corner.
As the home fans celebrated to a backdrop of Chelsea Dagger by The Fratellis, Carlisle landed a conversion that reduced the arrears to 16 points.
But Saints weren’t prepared to sit back for the final 20 minutes and instead pushed on, grabbing a penalty try after a shove proved too much for Treviso in front of their posts.
Myler’s conversion took the scoreline to a comfortable 33-10 and Treviso were soon down to 14 men again as prop Romulo Acosta was binned for standing up in the scrum.
But the men in white were soon celebrating a second score as Carlisle intercepted Stephenson’s pass and sprinted to the line from inside his own half.
The fly-half, clearly fatigued by flying over the line, left his conversion attempt well short before Saints were forced into two last-ditch interventions to prevent a third try.
And it was to be Saints who had the final say as Pisi flew over to ensure his comeback concluded in style.
Myler hit the post with the conversion, but it mattered not as the men from Northampton celebrated a fine European away success.
Treviso: Hayward; Ragusi, Campagnaro (Morisi 40), Christie, Nitoglia; Carlisle, Lucchese; Muccignat (Zanusso 43), Giazzon (Kudin 66), Manu (Acosta 39); Minto, Pavanello (c); Favaro, Zanni (Barbini 14 (Fuser 64)), Budd.
Saints: Foden (Wilson 61); K Pisi, Stephenson, Burrell (G Pisi 56), Elliott; Myler, Dickson (Fotuali’i 51); A Waller (E Waller 54), Haywood (Hartley 61), Denman (Mercey 54); Dickinson, Day (Lawes 66); Clark (Wood 54), Dowson (c), Manoa.
Referee: Peter Fitzgibbon (Ireland)