February 2, 2008. A date etched in D'Arcy's mind forever. The day he shattered his right arm in eight places when tackling Italy's Andrea Masi in an RBS 6 Nations game at Croke Park.
Ireland went on to beat the Italians 16-11 but the win was clouded by the loss of D'Arcy and the Wexford man, who required three operations on his arm, faced a comeback of monumental preportions.
A six-inch titanium plate had to be inserted in his forearm but gradually, with a lot of patient work from the player himself and the medics, the injury fully healed.
What has made D'Arcy's return to fitness and Test level rugby all the more remarkable and satisfying is the whirlwind five months he has experienced since returning in Leinster blue on a chilly Belfast night against Ulster on December 27 last.
A Grand Slam winner, a Heineken Cup winner, a try-scoring debut for the Barbarians and now a call-up to the Lions tour in South Africa.
No doubt his 11 months out of the game have made him appreciate everything more, from lacing up his boots to collecting medals and trophies, but reflection time is for further down the line.
He has some serious business to attend to, beginning this Saturday in Bloemfontein.
Relaxing at the Lions team hotel, D'Arcy took us through a hectic few days which saw him having to postpone a well-earned holiday in America before it had even started.
"There's been a lot of travel but it's probably the one phonecall you don't mind getting when you're on holidays," he explained.
"It was a hell of a journey and I wasn't actually on holiday. I hadn't even arrived. I was at the airport in San Francisco and I got the call from the Lions and turned straight back around."
He added: "It's been a fantastic couple of months. This is, I suppose, a perfect cap-off to the season.
"I got out here as soon as I could. They said if I can get out here, I'd be on the bench.
"So there's no point messing around. I got the first flight out here. No boots, no gumshield, no nothing...just get out here and worry about the rest of it later."
The boots situation was sorted with a short shopping trip, although D'Arcy admitted that he got 'the ugliest pair of boots that were there.'
The 29-year-old will have to play catch-up on his rivals for the Lions inside centre spot, in terms of training, acclimatisation, game-time and general tour and squad specifics.
Helped by his run-out for the Barbarians against England at Twickenham last weekend, D'Arcy said: "(The learning curve) is only as steep as you make it. At the end of the day, rugby's not the most complex game in the world.
"Calls are pretty much all you have to learn. The players around you (with the Lions) are as good a bunch of players as you're going to get.
"I think probably the perfect preparation for it was the Baa Baas, because you just go out and run lines, you run hard and you just rely on other players being as good and knowing what you're doing.
"Obviously it's a lot more structured than the Baa Baas, but the same basic premise applies. You get the best players in the world and you put them together on a pitch.
"I'm obviously not going to be completely up to speed with the intricacies of the major game plan and the overall game plan but, at the end of the day, it's not all that hard to get the ball and get over the gain-line."
Returning from such a serious injury, D'Arcy admitted that featuring on his second Lions tour - he played six games on the 2005 tour to New Zealand, as well as the warm-up Test against Argentina - was understandably not one of his goals for this season.
"In November last year, I had just had my third operation on my arm. It kept me out of rugby for 11 months altogether.
"At the start of the season I wasn't really thinking of the Lions, just playing rugby was good enough. There were a few dark days, but I'm confident now that I'm back."
Back in a big way with Leinster and Ireland and now he intends on pushing for selection in the Lions' upcoming Test series against South Africa.
The first chance to impress should come at Vodacom Park this weekend where the Cheetahs lie in wait.
"There are plenty of games left on tour. I have come out to fill in for certain injuries at the moment but if I carry my form in, you never know what might happen," he said.
"Jamie Roberts and Brian (O'Driscoll) played fantastically well on Wednesday night. But in the same way that I had a little candle burning to get a call to come out here, I still have a little candle burning that I can force my way into the Test side."