Racing 92 34 Munster 30
As the clock ticked towards the 80th minute at the U Arena, the game within the game became more and more intense.
Both teams wanted to win the match, but there were ramifications beyond the result. A fourth try for Racing would have swung Pool 4 in their favour ahead of their final game away to Leicester Tigers, while the losing bonus point Munster clung to would be enough to make the equation simple next week against Castres at Thomond Park.
So, when Ian Keatley skewed a kick in his own '22 and Jean Kleyn was guilty of killing the ball under his posts, the Munster coaching team had their hearts in their mouths.
When Maxime Machenaud pointed to the posts, they breathed a sigh of relief.
Racing had decided that the win was more important. The way results worked out over the course of a mad weekend of European rugby, they are well-placed to go through as a best-runner-up if they win in Welford Road next week and that was a better prospect than leaving Munster in the game.
"Yes, very much so," Johann van Graan said when asked if he was relieved at that moment.
"Our initial reaction was if they go for a scrum that's the hardest scrum to defend and they mauled pretty well with their massive players, so very relieved about that.
"As a squad, we're all disappointed about this one. It was a very different occasion to what Munster's used to and to have been in front with two minutes to go and let this one get away is disappointing but I'm going to take the positive out of it and very glad about that bonus point.
"It's the first time I've been involved in this competition and even watching the games last night; every single minute matters from the first against Castres right through to the last against Castres now.
"It's pretty simple, we go back to Thomond Park, we start at zero, we prepare well and if we win we've got a quarter-final."
Failure to win in Paris may cost the Reds a lucrative Limerick fixture in the last eight and Castres' bonus-point win at home to the Tigers means the French side - currently third in the Top 14 - are still in the mix.
Traditionally, they have sent weakened teams to away games but that is unlikely to happen on Sunday. If they can win at Thomond Park and deny Munster a bonus point, then they'll finish above the Irish side on head-to-head. It might be a long shot, but it retains the south of France side's interest which has usually long-waned by this point.
If Munster can produce their best, they'll go through and the signs are that they are developing an attacking game that will make them a dangerous opponent when the season reaches its business end.
At times, particularly just after both kick-offs, they looked like they might be blown away by Racing who scored within three minutes of the whistle in both halves.
But when the game settled into a pattern, it was the Reds who looked the more dangerous team and, while the world and its mother is waxing lyrical about young Jordan Larmour, Keith Earls served a reminder of just how good he can be with a devastating display.
They fought back from 18-7 down to lead 21-18 and then the lead changed hands four times during an exciting, frenetic second half.
Played beneath the roof at the space-age, surreal new home of the Parisian side, the pace was relentless and that suited Munster more as the game went on.
They were 10-0 down after eight minutes thanks to Yannick Nyanga's try and the pristine boot of Machinaud, pulled a hard-earned try back through Kleyn but then hit the post twice with kicks at goal before Peter O'Mahony handed the scrum-half a chance to edge his side further in front on the cusp of half-time with a needless comment to the referee.
Racing started the second half like a train and as Munster's tackling failed them Marc Andreu scored, but a superb individual effort from Earls and a well-worked Chris Farrell score put the visitors in front by 21-18.
Then, the kickers took over with Machenaud levelling before two Keatley efforts put his side six in front.
A cleverly worked lineout try for Dimitri Szarzewski and a precise conversion from Machenaud put the French side back in control, but Conor Murray then nailed a penalty from inside his own half to give Munster the lead going into the stretch.
They'd have backed themselves from there, but Donnacha Ryan claimed the restart superbly and when Jack O'Donoghue played the ball on the deck the scrum-half put his side back in front.
Then came the big decision. Keatley skewed a clearance and it landed in Virimi Vakatawa's lap.
On the back foot, Kleyn went off his feet and killed the ball. Racing had their moment to wrest control of the pool, but perhaps with a nod to Munster's quality, they took the conservative option.
"It's hard with five minutes to go. We could have put them four points away so they had to score a try, it's different to a point where they could get a penalty and then it's over for us," Nyanga said.
"We were thinking, but it happened fast and we'll see after the game against Leicester if it was a good decision or not."
So, the pool goes down to the wire and after a weekend of surprising results the path to the quarter-final is now open to both teams.
"I said to the lads in there, it just shows what an amazing competition this is," Van Graan said.
"That's what we love and want to embrace. The players want to play in big games and this is a big game at home. We can't wait."
All roads lead to Thomond.
Racing 92 - L Dupichot (J Rokocoko 73); T Thomas, V Vakatawa, H Chavancy, M Andreu; R Tales, M Machenaud; E Ben Arous (V Kakovin 53), C Chat (D Szarzewski 53), B Tameifuna (C Gomes Sa 48); D Ryan, E Maka (B Palu 48); Y Nyanga, W Lauret (B Chouzenoux 76), L Nakarawa.
Munster - S Zebo (A Wootton 73); A Conway, C Farrell, R Scannell, K Earls; I Keatley (JJ Hanrahan 79), C Murray; D Kilcoyne (J Cronin 56), R Marshall (K O'Byrne 75), S Archer (J Ryan 56); J Kleyn, B Holland; P O'Mahony (J O'Donoghue 55), C Cloete, CJ Stander.
Ref - M Carley (England)