It's a game that will always be remembered as 'Bloodgate' but the controversy tends to overshadow a Nick Evans drop goal that could have rewritten rugby history and a 2009 Heineken Cup quarter-final that had so many more layers to it. Brendan O'Brien takes a look back
There were 45 seconds left when the ball spun back towards Nick Evans. The former All Black out-half had one working knee and he was close to 40 yards out with Chris Whitaker about to jump in his face but he was fairly central and the underfoot conditions were good.
The Kiwi had the benefit of a trial run just four months earlier when, with 'Quins trailing Stade Francais by a point at the same venue and four minutes of injury-time already played, he scuttered a drop goal through the posts after 29 phases. It needed the TMO to make sure that it went over but the job was done.
What if this kick had gone over, too? What if Harlequins had won 8-6 instead of lost by one? It's hard to see how they would have beaten Munster in the semi-final at Croke Park. Odds are that the Red Army would have marched on to Edinburgh for the final and a crack at a third title in four years.
And what of Leinster?
Michael Cheika was four years into his Operation Transformation at the time. The squad was using portakabins for dressing-rooms when he arrived. They still had no defence coach when Whitaker landed from Australia to play scrum-half a year later. Imagine.
There had been clear signs of progress. The quarter-final win away to Toulouse in 2006 was a performance for the ages and they had claimed the Celtic League in 2008 but the lows were still subterranean and all too frequent.
There was a dreadful performance away Edinburgh in Europe the year before, a crippling loss to Castres three months before the 'Quins game and a 17-point loss in Limerick the week before this which, for all their good play, only seemed to solidify Munster's superiority.
Cheika was contracted for another season but there was a body of opinion that he wouldn't make it that far if Leinster fell this far short in Europe again. Felipe Contepomi had already announced that he would join Toulon that summer and Whitaker was months from retirement.
Leinster might have had an abundance of talent at the time but there was nothing to guarantee that they were on the brink of becoming Ireland's and the continent's pre-eminent force. They were in a type of limbo which was summed up by a young Jonathan Sexton.
The out-half was suspended for the quarter-final having kicked out at Lifeimi Mafi in that loss to Munster and one of the clearest memories of the day is that of Sexton sitting alone in a hospitality suite watching Munster destroy a very good Ospreys side in the earlier game at Thomond Park.
Little did he or anyone else know then how his life would change just weeks later in Croker.
Harlequins had won nine of their previous Premiership games under Dean Richards and, while they didn't have any real 'star' names at the time, they were well-stocked with a core of players who would go on to enjoy hugely successful careers at international level.
Mike Brown, David Strettle and Ugo Monye made for a classy back three, the excellent Evans was partnered by a callow Danny Care in the half-back cockpit and Mike Ross, Chris Robshaw and Nick Easter were members of a well regarded, physical pack.
“Harlequins, maybe like ourselves, suffered from capital city syndrome,” said Leinster's Malcolm O'Kelly in the book 'Leinster: Conquering Europe'. “They were perceived as a team without heart, a team of glamorous flair and no real substance. But the 'Quins team we faced were young, keen and developing.”
Leinster's reputation had been stained by the infamous 'Ladyboys' moniker and an inability to get over the line on the biggest of days but lazy stereotypes were miles wide of the mark on a day that would prioritise character and courage rather than class.
There was a point earlier in that season when the province had gone six weeks without scoring a try and Rocky Elsom, their talismanic Aussie flanker, pointed out later how they had simplified their game plan during the Six Nations when the internationals were away.
This was anything but bling.
There have been only 23 games in the history of the European Cup when neither team has recorded a score in the double digits. Only the 3-3 stalemate between Bath and Toulouse at the mud-pile that was The Rec that January produced less points than this.
Leinster's attacking offerings were limited. A Brian O'Driscoll kick and catch here, a rampaging run from Elsom that he would repeat at a crucial stage of the decider against Leicester there. Rob Kearney did have a try ruled out though and there was a shout for a penalty try too.
Harlequins would leave eight points them from kicks. Most annoying was a sitter of a penalty that Evans botched in the first-half but it's that last-gasp drop goal that lives in the memory after all the shenanigans and recriminations.
Leinster knew what was happening. The team operations manager, Ronan O'Donnell, was steaming on the sideline. He tried in vain to protest to Nigel Owens when Tom Williams came off with a faked blood injury and Evans, taken off after 47 minutes, came back on in his place.
Munster had been denied a first Heineken Cup seven years earlier by the 'Hand of Back' but this was a whole new depth of dark art and it left Leinster with a sense of helplessness as the hobbling Evans was manoeuvred into position.
“We could see all of the drama that was unfolding with the Nick Evans 'blood' substitution,” said Girvan Dempsey later. "We had played so well and there was a sense that they were trying to cheat us out of our place in the semis.
“When he lined up that kick, having come on in such controversial circumstances, you just sensed the worst, but when the drop goal fell wide in the last minute of the game there was a feeling of relief, delight and destiny.”
Not everyone felt their name was on the trophy. Munster were deemed odds on favourites to claim the trophy after that weekend, Leinster were out as far as 7/1. Still, they were alive, if only just, and they would make the most of the escape against Munster and again in the final.