Ten years on and Devin Toner still can't the game out of his system.
Ireland, under then coach Joe Schmidt, were seconds away from beating New Zealand for the first time when Ryan Crotty's converted try broke Irish hearts at the Aviva Stadium.
Even though Toner was present when Ireland eventually broke their All Blacks duck three years later, and again for victory over New Zealand in 2018, the scars remain.
The pain is etched in the memory alongside Leinster's defeats to Saracens in the Champions Cup final in 2019 and the quarter-final a year later.
So the former Ireland lock is in no doubt that Leinster's loss to La Rochelle is going to haunt his old team-mates for a long time to come.
Given where the match came in the team's evolution, that it signalled the end of both Johnny Sexton and Stuart Lancaster's time, and where the actual trauma took place, at home, there's no escaping the fallout will be worse than any defeat suffered previously.
"First one is the All Blacks in 2013 that we lost in the last second, that sticks out the most," replies Toner, almost immediately when asked which one comes to mind.
"The Saracens one as well was big.
"But if you have success over the next couple of years then they kind of fade away a bit but again the one for Leinster, the La Rochelle one, will haunt them for a lot now.
"Because obviously Johnny moved on, Stu moved on, it's three years that we've lost to them: semi-final, final, final so that will stick for a while.
"If you go ahead, turn around and win it next year it will be forgotten about a little bit but it's obviously the success that happens after that that will put it to the back of your mind."
Lancaster's departure will be somewhat mitigated by the arrival of Jacques Nienaber the South Africa World Cup-winner coach (above), who will join up after the RWC in France in October.
"He will probably bring a renewed energy to the squad, he might take a couple of weeks to bed in but I think it will be interesting to see how it goes," said the 36-year-old.
"It will be hard to see Stu leave because he has had such a phenomenal impact at Leinster over the last seven years, and it will be a different landscape seeing Johnny gone and it will probably be a little bit of a fresh start."
Toner was speaking at the at the launch of Aviva Ireland's Pride socks, with all proceeds going to BelongTo LGBTQ+ Youth Service.
Over the last two years, former team-mates of Toner, Jack Dunne, now at Exeter, and Nick McCarthy, who has just left Leinster, spoke openly about their sexuality.
Having started his professional career 17 years ago and finished up last season, Toner says he has seen a change in the environment.
He said: "I came into the squad around 2006 and the landscape has changed in 20 years.
"Thinking back on it, I think it would have been harder for someone to come out then than it is now.
"The landscape has changed a bit and it is a bit more accepting. Well, you’d like to think it has anyway.
"Nick felt comfortable doing it. Like he said, he didn’t have any negativity from anybody and I think it was a really good environment to do it.
"I was just saying to him that we need to get to a place where he doesn’t have to come out. People are who they are."
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