And so they wait. The cruellest of ironies for back-to-back Heineken Cup champions was confirmed at a raucous Sandy Park – their qualification fates lie in the hands of their most fierce rivals from Munster.
The three-time champions left Exeter with heads held high after securing the bonus-point victory they required to retain a fingertip grip on their cherished crown.
But they will arrive back in Dublin later tonight night slowly grasping the grim reality that Munster stand prepared to topple it from their heads by merely matching this result against a severely weakened Racing Metro side in Thomond Park tomorrow.
They could have done little more to maintain their interest in Europe’s greatest prize on an intoxicating, at times surreal evening, in the bitterly cold south-west of England.
Indeed, at times, it seemed as if coach Joe Schmidt’s anxiety about not at least securing the victory threatened to become a terrifying reality, as this immensely proud Exeter side, ostensibly with little but pride to play for, contributed so handsomely to a captivating contest that toyed with the emotions of the awestruck 10,000 attendance.
At the very least, Leinster will be able to rely on some form of European competition – they just will not know until events unfold later today whether that encompasses an improbable assault on an unprecedented Heineken hat-trick, or a stint in the relatively unloved second tier Amlin Challenge Cup.
After Montpellier had unleashed a sense of fury into their submission of Toulon earlier, while Leinster were practising their lineout drills in their hotel car park, it left what had seemed such a complicated mathematical prognosis suddenly seem infused with clarity.
Leinster needed to get the hurry on and compile a sufficient try and points buffer to make their southern provincial rivals sweat a bit harder ahead of their Sunday lunchtime assignment.
They began their quest like men possessed and the tries scored by Gordon D’Arcy and Rob Kearney, featuring some sublime interplay between forwards and backs, not to mention genius handling from Brian O’Driscoll, showed us what they had been missing for much of their title defence.
Only at lunchtime tomorrow will we know whether their sparkling return to familiar form arrived too late to save them.
That Exeter sandwiched Leinster’s opening two tries with a superlative effort of their own reflected the manner in which the home side were willing to summon up stout resistance to what many visiting fans may have assumed was a merely mathematical exercise.
Leinster can only wish that the French are as devoted in their credibility to the competition tomorrow.
A penalty try and a Gareth Steenson penalty pushed Exeter 17-12 ahead at half-time and it needed all Leinster familiar fighting qualities in this competition to row back the tide in the second-half.
O’Driscoll, of course, was central, nabbing his side’s third try before the man who replaced him as Irish captain, Jamie Heaslip, secured the bonus and the buffer of a 26-17 lead.
Exeter, rebuffing penalty attempts with the same alacrity as their opponents, finally took a three-pointer in a cliff-hanging final quarter before Jonny Sexton, having himself spurned so many, finally decided to secure the victory with the final score a breathless encounter.
They will continue to hold their breaths tomorrow. Holding out for a miracle, perhaps. But at least they will have rested in relative comfort, knowing that they held up their part of the bargain.
Any other regrets must await another day.
Follow independent.ie's live blog of the crunch Munster match tomorrow from 12.15.