Northampton Saints set up a tantalising decider with Munster by recording a 34-0 win over Perpignan at Franklin's Gardens on Sunday, with Jon Clarke collecting the bonus point in the last play of the game.
The Irish giants top Pool One with 20 tournament points and play hosts to the Saints, on 18, in a winner-takes-all clash at Thomond Park on Friday night.
All hope of a bonus point seemed lost after the Saints turned in a deathly slow start. But they manage to conjure up four tries in the second period, with Clarke sealing the deal by getting on the end of improbable length-of-the-field move in stoppage time.
The turnaround was inspired by the dancing feet of Ben Foden, who set up the first two tries by counterattacking from depth. Martin Johnson might just have the best night's sleep of his England tenure.
But the exclusion of Shane Geraghty from his plans might yet have the big man tossing and turning: the fly-half stood flat and aggressively and was canny in attack and defence.
It's cliched to talk of matches of two halves, but in this case it is entirely merited.
With nothing to lose and perhaps smarting with reports suggesting they were part of a second-string side, the visitors tore into the game and won an immediate penalty within striking distance of the posts. But the reverential silence of the crowd seemed to spook Steve Meyer and the South African's kick drifted wide.
Perpignan continued to push and their cavaliering ways held sway for the first quarter of the game.
Indeed, the Saints didn't manage to break into Perpignan's 22 until Meyer was sin-binned in the 16th minute for impeding a quick-tap penalty from Lee Dickson. It was Foden who led the charge into French territory, but Geraghty was unable to goal the penalty after the full-back's raid was punctuated by a high tackle.
The locals failed to make the numerical advantage count, but Geraghty did got another bite of a cherry in the 26th minute after Perpignan conceded a penalty at a scrum, and the match scorer was finally roused from his slumber.
There was more good work from Geraghty's boot after Adrien Plante went chasing after a long grubber. It looked like the wing had dotted down, but a video referral confirmed that the Englishman had managed to hack the ball away from the Frenchman's grasp.
The scare forced the Saints to up the ante and momentum finally began to build. The pressure began to tell and Geraghty soon doubled his side's lead after Perpignan were forced to kill the ball in defence.
But half-time oranges must have tasted like lemons. The Saints would have been expecting more than a meagre 6-0 lead at the break.
They emerged for the concluding stanza with boot marks on backsides and began to play with more purpose.
An aimless kick from Perpignan was run back by Foden. A dummy opened the door to a searing break and Chris Ashton was on hand to take the final pass and score. Geraghty added the extras and the Saints were up and running.
Phil Dowson picked up the Saints' second score in the 54th minute, with the flank being the beneficiary of another silky break from Foden. Set free by a long miss-pass from Geraghty, the England hopeful found Ashton on his outside and the wing drew three defenders before feeding the ball out to the supporting forward.
Geraghty converted and Franklin's Gardens began to believe: two tries down, two to go.
The next score was born from a superb rolling maul, with Neil Best breaking off to feed Dickson who dived for the line. Replays suggest he didn't quite make it, but referee Alain Rolland saw fit to award the try without the need to trouble the TMO.
Geraghty converted and belief fell away to expectation.
But still Perpignan refused to lie down and they had the better of the final ten minutes. The Saints huffed and puffed but there didn't seem to be any way out of their own half.
But suddenly the French were in reverse and the Franklin's Gardens faithful rose as one to see Clarke scamper over at the death.
The win stretches Northampton's winning run to ten matches - but it's that eleventh one that really counts. Despite the day's excitement, this is but the calm before the storm. Next week will be titanic.
For Northampton Saints:
Tries: Ashton, Dowson, Dickson, Clarke
Con: Geraghty 3, Myler
Pens: Geraghty 2
Yellow card(s): Meyer (Perpignan) - professional foul, 16.
Northampton Saints: 15 Ben Foden, 14 Chris Ashton, 13 Jon Clarke, 12 James Downey, 11 Bruce Reihana, 10 Shane Geraghty, 9 Lee Dickson, 8 Roger Wilson, 7 Neil Best, 6 Phil Dowson, 5 Juandre Kruger, 4 Ignacio Fernandez Lobbe, 3 Brian Mujati, 2 Dylan Hartley (capt), 1 Soane Tonga'uiha.
Replacements: 16 Brett Sharman, 17 Alex Waller, 18 Jon Vickers, 19 Christian Day, 20 Scott Grey, 21 Alan Dickens, 22 Stephen Myler, 23 Chris Mayor.
Perpignan: 15 Philip Burger, 14 Adrien Plante, 13 Jean-Philippe Grandclaude, 12 Gavin Hume, 11 Christophe Manas, 10 Steve Meyer, 9 Florian Cazenave, 8 Grégory Le Corvec, 7 Jean-Pierre Perez, 6 Guilhem Guirado, 5 Rimas Alvarez Kairelis, 4 Yoann Vivalda, 3 Benoit Bourrust, 2 Marius Tincu, 1 Sebastien Chobet.
Replacements: 16 Charles Geli, 17 Jérôme Schuster, 18 Kisi Pulu, 19 Robins Tchale Watchou, 20 David Mele, 21 Joffrey Michel, 22 Nicolas Laharrague, 23 Yannick Parent.
Referee: Alain Rolland (Ireland)
Assistant referees: Dudley Phillips (Ireland), Eanna O'Dowd (Ireland)
Television match official: Brian Fitzgerald (Ireland)