Should the Saints beat the Warriors not even a bonus point victory for Exeter at Saracens would deny the men from the Gardens, who are ahead of the Chiefs in terms of games won.
But as the Chiefs dominated much of the first half, taking advantage of the strong wind to push Saints back time and again, heading back up the M5 with the four league points looked a long way off.
However, the Saints started well, winning back a turnover and then forcing Phil Dollman to hold onto the ball in a tackle. This allowed Stephen Myler to push his team deep into Chiefs territory, and with some good ball retention and nice awareness of the supporting players play was worked into the home 22.
A penalty, and the three points that came with it, was a suitable reward. But while the visitors may have got off to a good start when Lee Dickson was ruled to have been in front of a Myler bomb it set in train an attack which brought the first sight of whitewash.
Haydn Thomas's quick tap put Saints onto the back foot, and when the visitors infringed again 20 metres upfield the scrum-half did the same again, with the same effect. This time the defence ran out, and although referee Andrew Small referred the play to the TMO the home confidence was well placed, Gonzalo Camacho being awarded the try.
Ignacio Mieres landed the extras, and when the Argentine used the strong wind to send a penalty touchfinder to the right corner it set up another superb position for the hosts.
However Jason Shoemark fumbled, Exeter engaged early at the scrum and although Myler's Garryowen handed possession back to the hosts Dollman's return went straight into touch to give Saints a decent attacking position.
A penalty in the subsequent play brought a lineout 10 metres from the home line, but this time Saints failed to make the most of the position. Instead the Chiefs turned the ball over, Mieres sent a great kick to the far corner, and although the defence held out some determined charges a penalty was forthcoming.
The three points were a formality, but Mieres nearly handed Saints a try from the kick off, his floated pass coming agonisingly off George Pisi's fingertips. The balance of play was nevertheless still with the hosts, with Thomas and Camacho combining again in a dangerous attack.
For their part Saints were struggling to hold onto the ball when they got it, and even though a combination of strong scrum pressure and good work from James Craig won a penalty back the wind proved too strong for Myler, whose shot at the sticks was blown right.
Saints' only other half-chance of the opening 40 minutes came a couple of minutes before the break, but even the normally reliable grubber kick down the wing - so profitable so many times this season - rebounded away from the chasing Chris Ashton and into a grateful Chief's hands.
In the meantime play remained rooted in the visitors' half, and by the time the whistle blew for half-time the travelling supporters would have taken just the seven-point deficit.
That was because Exeter had three gilt-edged chances, but a combination of a Pisi tap tackle on Mieres, Ben Moon somehow being held up and the fortune of it being tighthead prop Hoani Tui recovering an up-and-under rather than one of the speedier players from the backs meant that the hosts failed to add to their try tally.
Mieres also missed a penalty, which meant that when play restarted Saints were still within a score.
Within two minutes of the resumption of play the deficit had been cut by five thanks to a superb try. It had been an inauspicious start, though, Roger Wilson leaving the ball behind as a Saints scrum drove forward. Dickson recovered quickly though, both to find Myler but then also to loop around to create an overlap. Pisi found Ben Foden, who in turn put Chris Ashton over in the corner.
Myler's conversion came close to tying the scores, but the try was exactly what had been needed after all the defence of the first half, as was the sight of Mieres missing an ambitious shot at goal.
Having started so well, Saints were unable to apply consistent pressure, partly through an unlucky bounce which saw a rebound come too quickly to Ashton for the winger to collect, partly through fumbles here or there which handed possession back to the hosts.
However while in the first half this led to the Chiefs hammering away at the visitors' line, in the second period the hosts seemed hesitant, content to go through the phases and work off their set piece rather than maintain the fast tempo which had been so successful earlier on.
This was no more true than when Camacho got the ball in his hands at a penalty. In the first half he would have tapped and gone, seeking to take advantage of the disjointed Saints defensive line. But instead the ball was thrown to Mieres to go for territory.
However by then the Chiefs were behind, thanks to Myler's second penalty. And while their set piece had gone well in the first half, in the second Saints' forwards went through the gears to put pressure on lineouts and win several scrums against the head.
It did not matter who was on the field for the visitors, the result was the same, and when the replacement front row won a scrum against the head on the Exeter 22 it gave Wilson the platform to run from the base. Paul Diggin was in support, and the winger's pace, step and power took him over the line.
The celebration reflected Diggin's new arrival into the family earlier in the week, but while it was important it was nothing compared to Myler's successful touchline conversion, which drifted perfectly from left to right and between the uprights.
This put Saints eight points clear with less than five minutes to play, but while Exeter legend Richard Baxter marked his 350th appearance for the club with a last-gasp try, all this did was give the hosts a losing bonus point, with the Saints instead in pole position for a place in the Aviva Premiership Rugby semi-finals.
REFEREE Andrew SMALL
TIMELINE
6mins SAINTS Pen Myler 0-3
9mins CHIEFS Try Camacho Con Mieres 7-3
17mins CHIEFS Pen Mieres 10-3
24mins SAINTS Miss pen Myler
32mins CHIEFS Miss pen Mieres
HALF-TIME CHIEFS 10 SAINTS 3
42mins SAINTS Try Ashton 10-8
46mins CHIEFS Miss pen Mieres
63mins SAINTS Pen Myler 10-11
75mins SAINTS Try Diggin Con Myler 10-18
80mins CHIEFS Try Baxter 15-18
FULL-TIME CHIEFS 15 SAINTS 18
