Saints concluded a turbulent 2018 in incredible style as they secured a bonus-point 31-28 success against Gallagher Premiership table-toppers Exeter Chiefs.
It was a raucous atmosphere under the Friday night lights at Franklin’s Gardens, and Saints certainly rewarded the sell-out crowd with a sensational showing.
It was an electric start from Chris Boyd’s side as they came flying out of the blocks, scoring twice in the opening 10 minutes through Piers Francis and Dan Biggar.
But Exeter came roaring back, using their incredibly dominant scrum as a platform to level the scores.
Saints refused to be deterred though, scoring again through Fraser Dingwall, who came on for the injured Francis after just six minutes, to take a 21-14 half-time lead.
Alex Waller was yellow carded as Saints continued to be hit hard at the scrum, and Exeter scored their third try just before the prop returned to the field.
But Reinach claimed his second superb intercept try in as many weeks and after Biggar added the conversion and a penalty, after Luke Cowan-Dickie was yellow carded for a tip tackle on Courtney Lawes, confidence was starting to flow.
Exeter did everything they could to get back in the game but Saints’ defence had been superb in open play all night.
Matt Kvesic eventually broke down the wall from a lineout drive to ensure Exeter would leave with two bonus points, but it was Saints who were celebrating a memorable success to a chorus of cheers at the final whistle.
It took the black, green and gold up to fourth in the league standings, ensuring they would enter 2019 on a high.
Saints’ determination was on show from the start as Tom Collins broke from inside his own half, turning on the turbos as he left Exeter players trailing in his wake before Dan Biggar flicked the ball up for the onrushing Francis to score.
Biggar converted to make it a perfect opening for the black, green and gold, but they were soon hit by an injury blow as ecstasy turned to agony for Francis, who looked to be in real pain as he headed off the field to be replaced by Fraser Dingwall.
But that did not deter Saints as they marched on in relentless fashion, with Collins going close before the ball was moved to Biggar to stretch out and score his first Saints try.
The fly-half easily converted from in front of the posts to make it 14-0 inside the opening 10 minutes, and Exeter were all at sea.
The Chiefs were struggling at the lineout, with Saints disrupting them at every turn, but the home side just couldn’t clear their lines as they failed to gather the bouncing ball cleanly.
And Saints were made to pay as after conceding a succession of penalties, referee Ian Tempest eventually took the decision to award a penalty try a scrum five metres out.
Exeter were now well on top, using their scrum as a wrecking ball and after Luther Burrell missed a tackle, the Chiefs showed their ruthless edge, sending Santiago Cordero over in the corner.
Gareth Steenson added the extras from the touchline and the scores were level nine minutes before the break.
Exeter were looking ominous but Saints refused to be floored and after the Chiefs lost the ball after a scrum on their own 22, Dingwall spotted a gap and dived over under the posts.
It was a magical moment for the young man, and Biggar put the icing on the cake with the conversion to put his team 21-14 up in an enthralling encounter.
But Exeter were straight back in Saints’ faces, forcing Alex Waller to infringe at a scrum, with the skipper sent to the sin bin.
The Chiefs went for the corner and after being held up once, they thought they had scored through Ollie Devoto, but Dingwall had done enough to get his arm under the ball.
And Saints continued to stand tall in open play as Burrell made a huge hit to force a knock-on and bring the half-time whistle from Tempest.
Exeter started the second half on the front foot though and just before Waller returned from the sin bin, Ben Moon got the score that allowed Steenson to convert and level the scores at 21-21.
The Saints fans were far from happy with referee Tempest, who was whipping up a scrum storm, but the home players were certainly inspired by the noise of their support.
And after Exeter saw a pass from a lineout pouched by Reinach close to halfway, there was no stopping the speedy South African, who scored his second interception try in as many matches to bring up the bonus point for Saints.
Biggar converted and ‘come on you Saints’ echoed around the ground once more.
Belief was starting to grow among those of a Northampton persuasion, and it increased further when Luke Cowan-Dickie was sin-binned, three minutes after coming on, for a tip tackle on Courtney Lawes.
The Saints supporters were baying for a red card in what could certainly be viewed as a controversial call, but Biggar turned the boos to cheers by slotting the resulting penalty.
Saints were now 10 points up with 17 minutes to go and they did brilliantly to win a penalty from an Exeter lineout drive that looked to be heading over the try line.
Exeter continued to huff and puff but they could not blow down the Saints door, which was reinforced by relentless noise from the home fans.
The Chiefs were still searching for the try that would let them leave the Gardens with two bonus points and they got them thanks to a lineout drive, finished by Matt Kvesic.
Steenson converted, but it wasn’t enough as the Gardens celebrated a memorable success for their side.
Saints: Tuala; Collins, Burrell, Francis (Dingwall 6), Naiyaravoro; Biggar, Reinach; Waller (c) (van Wyk 53), Marshall (Fish 60), Hill (Franks 53); Ribbans, Lawes; Gibson (Wood 55), Ludlam (Brüssow 55), Harrison.
Exeter Chiefs: Simmonds (Dollman 72); Cordero, Whitten, Devoto (Slade 55), O’Flaherty; Steenson (c), Maunder (White 55); Moon (Hepburn 53), Taione (Cowan-Dickie 59), Williams (Francis 53); Lees (Hill 54), Skinner; Lonsdale (Lawday 70), Armand, Kvesic.
Referee: Ian Tempest