Stephen Myler displayed nerves of steel to earn Saints a 17-15 win with the final kick of the game against Wasps at Adams Park.
The fly-half superbly landed a late penalty to make sure home No.10 Joe Carlisle’s three-pointer two minutes from time was rendered meaningless.
Carlisle looked to have snatched the win for Wasps, but Myler, who racked up a total of 12 points on the day, kept his cool to secure a vital four points.
Christian Day’s first-half score and Myler’s boot put Saints in the ascendancy, but Wasps refused to go away, with Elliot Daly, Andy Goode and Carlisle keeping them in contention.
Tom Wood’s sin-binning with 10 minutes to go looked to have hampered Saints’ cause.
But they stayed calm to come through a tricky fixture in tough conditions to keep pace with table-toppers Saracens and show their Premiership title credentials.
Both teams had used the high ball without much reward early on, but Wasps did win a penalty when Luther Burrell was deemed to have taken out Goode late when the fly-half had kicked the ball on.
With Goode needing treatment, full-back Daly stepped up and placed the ball between the posts to give the home side the lead.
Saints thought they had landed an immediate counterpunch as Wasps failed to gather the kick-off and the ball bounced through for Burrell, who dotted down.
But the away side were harshly denied by the TMO, who penalised Day for a shirt-pulling offence in the build-up.
Day, who scored the winning try in the corresponding fixture last season, wasn’t to allow Saints to be denied for long, though, and he got on the end of a lineout drive to score.
Myler missed the conversion, but Wasps also fluffed their lines at the other end as Daly lashed his penalty attempt wide of the posts.
Saints made the most of that reprieve as some lovely hands in midfield tied Wasps in knots and they offended, giving Myler the chance to slot a kick from in front of the posts.
But Goode, back on kicking duty after Daly’s earlier miss, cut the deficit to two with a penalty from the left after Saints failed to clear their lines.
And the Wasps fly-half, who was starting to dictate in what was a stodgy game, put his team in front, pushing another penalty through the posts after failing with a drop goal attempt.
Saints were back in front two minutes before the break as a big scrum gave them a penalty near halfway, and Myler did brilliantly to beat the wind and bisect the posts.
Goode attempted to reply with a drop goal before the break but his ambitious effort was lacking in direction and power as Saints went into half-time 11-9 up.
The fly-half was only able to last four minutes in the second half as an injury forced him off, with Carlisle coming on in his place.
Carlisle’s first involvement was to completely fluff a drop goal attempt from in front of the posts, giving Saints a reprieve with the pressure having built since the restart.
At the other end a Mike Haywood knock-on put an end to a promising Saints move, before Jim Mallinder called for the cavalry, bringing on captain Dylan Hartley and Tom Mercey.
The away side immediately won a penalty, putting pressure on Wasps, who handed Myler a chance to make it 14-9. He didn’t waste it.
But Wasps were refusing to go away and Carlisle’s successful penalty gave the home fans real hope of an upset.
Daly’s monster kick from inside his own half fell just short of giving his team the lead, but Saints were soon dealt a big blow as Wood was sin-binned with 10 minutes to go.
The flanker was deemed to have played the man without the ball and the TMO acted to give Wasps the advantage.
Daly missed the resulting penalty, but Carlisle made a better fist of his attempt with two minutes to go to put Wasps in front by a point.
But Myler’s last-gasp effort after a penalty had been awarded at the scrum gave Saints the win.
Saints: K Pisi (G Dickson 64); Elliott, North, Burrell, Collins; Myler, Fotuali’i (L Dickson 72); A Waller (E Waller 65), Haywood (Hartley 57), Ma’afu (Mercey 57), Manoa (Lawes 64), Day, Clark (Dowson 64), Wood (c), Dickinson.
Replacements not used: Stephenson.
Wasps: Daly; Helu, Bell (c), Hayter, Varndell; Goode (Carlisle 44), Davies (Simpson 62); Mullan, Festuccia (Lindsay 62), Cooper-Woolley (Swainston 64), Palmer, Launchbury, Johnson, Haskell (Thompson 65), Jones.
Replacements not used: Vea, Cannon, Suniula.
Referee: Matthew Carley