'Away game. Home atmosphere' was how the game had been tagged and the Saints fans certainly played their part, roaring their side back from 11-0 down and into the lead thanks to Phil Dowson's try and a near flawless kicking display from Stephen Myler - the man with his head in his hands after a crushing 60 metre blow cannoned back off the woodwork.
Sarries would have been thanking their lucky stars after a let off for three Charlie Hodgson misses - the fly half also failing with the conversion of John Smit's fourth minute try.
He did effectively create the score though, a well-judged kick through forcing Jamie Elliott into touch and the Sarries pack doing the rest, driving their hooker over. Hodgson was on the mark with a 50 metre penalty almost immediately from the restart and another line out maul four minutes later allowed him to extend the advantage.
Saints were playing with intent and pace though and while a series of forays would end frustratingly in errors, they would finally sweep through the home defence on 25. An initial dart by Ken Pisi was followed by another from Dowson and when the flanker burst through three tackles, he was in for a much needed Saints response.
The scrum continued to prove something of a stalemate but it was off the back of one such solid set-piece that the gap would close further, Lee Dickson darting forward and Myler rewarding his half back partner's efforts with a crisply struck penalty as Sarries failed to roll.
With just a point between the sides after an evenly matched first 40, how the teams came out for the second half would be crucial and having seen Hodgson miss from 50 metres, Myler guided over his third kick of the day from slightly closer than his Saracens counterpart.
The Premiership's record scorer was having a rare off-day and also went astray with his next two from the tee - the second the most inviting of the pair. Myler on the other hand wasn't in such a charitable mood and hammered over another from right on halfway to take the Saints five points clear with only the final quarter to play.
The good work of the pack was quickly undone though, a change of kicker doing the trick for the hosts as Owen Farrell registered an easy three-pointer and the England fly half's introduction marked something of a turning point, even if indirectly.
His second penalty made it six-apiece for the second half and edged Saracens back into the lead, who then did well to shake off pressure from a poor spill from Shalk Brits and a fine Ben Foden counter.
The game had moved up a gear but with both sides struggling to hold onto the ball, chances remained at a premium and the last would fall to the Saints. Rhys Gill foolishly not only picked up a ball that wasn't his, but in kicking it away moved the penalty right onto the limit of Myler's range.
stadiumMK held it's breath and while Myler struck it as well as any of his previous four successes, the bounce off the crossbar fell cruelly on the wrong side and Brad Barritt helped settle frayed Saracens nerves, booting the ball into touch.
8mins SAR Try Smit 5-0
11mins SAR Pen Hodgson 8-0
15mins SAR Pen Hodgson 11-0
25mins SAINTS Try Dowson Con Myler 11-7
37mins SAINTS Pen Myler 11-10
HALF-TIME SAR 11 SAINTS 10
44mins SAR Miss pen Hodgson
47mins SAINTS Pen Myler 11-13
50mins SAR Miss pen Hodgson
54mins SAR Miss pen Hodgson
59mins SAINTS Pen Myler 11-16
61mins SAR Pen Farrell 14-16
67mins SAR Pen Farrell 17-16
80mins SAINTS Miss pen Myler
FULL-TIME SAR 17 SAINTS 16