D'Arcy is coming to the boil at just the right time, last weekend's display against Italy being one of his finest in the green jersey. He is well and truly up to speed now after a calf strain delayed his departure for the Rugby World Cup.
Three starts are in the bag, including full games against the USA and Italy, and his storming break in the lead up to Keith Earls' first try against the Italians showed how threatening D'Arcy remains with ball in hand.
The Wexford man is clearly relishing his first crack at a World Cup quarter-final. "This is where we wanted to be (at this stage of the tournament). We've been saying it from the word go," he told RTÉ Sport.
"This is everything - all the training, all the talk, all the performances have been leading to this one point. Hopefully this kickstarts into something else, but we'll deal with this match first."
The Celtic clash is commanding huge attention at home and abroad and some feel it is just too tight to call, given the sides' familiarity with each other and the form they have both shown in the pool stages.
D'Arcy agrees that a close game is in prospect, admitting: "It might just be a turnover, it might be a try-saving tackle, it might be three points or getting a player sin-binned. There's not going to be much in it, you're looking at 5% either way."
Some would see the battle of the centres at Wellington Regional Stadium as a case of the old masters being up against the new pretenders.
D'Arcy (31) and Ireland captain Brian O'Driscoll (32) have been at the top of the midfield tree for many years, while Wales' Jamie Roberts (24) and Jonathan Davies (23) have only started 11 Tests together as a centre partnership.
The D'Arcy-O'Driscoll tandem has been hugely successful for Ireland, through a Grand Slam, four Triple Crowns and a number of wins over the Southern Hemisphere's best.
The Leinster pair has set a new world record for starting centres at international level, eclipsing the previous mark set by England's Will Carling and Jeremy Guscott (45 starts). Saturday's encounter will be D'Arcy and O'Driscoll's 47th start together for Ireland.
Apart from the advantage in experience, D'Arcy also feels he is really beginning to hit his stride now. "The more games I play the better I'm getting. I knew this was what I needed, I just needed game-time.
"The touches, the stepping, the timing, little things like that are getting better. It's not just me, everyone in the squad is getting better.
"The intensity is going up, everybody's getting the timing in the tackle, the defence is getting stronger."
Ireland's defending has been right up there with the best in the tournament to date. They leaked just three tries and 34 points during their successful Pool C run, with only South Africa and England managing to do better.
D'Arcy welcomes the fear factor of such a high pressure game, saying: "If you do something wrong now, the stakes have just gone up massively. if you drop a ball in your 22, you could be giving up a try. It's these little things now that are going to separate teams.
"Fear is a good thing, but as long as you control it. You have that fear of failure, I think that's a thing that has always driven an Irish team no matter what we've done. But it can't be a controlling factor.
"We've got to enjoy it and relish the challenge. We can't let one emotion dominate anything here, because if it does it's taking over and controlling us. We stay in control of everything but a little bit of fear is healthy."
So, what will it take to beat Wales this weekend? D'Arcy insists that Ireland need to raise their level of performance from the displays in the pool stages, something which is well within their grasp.
"The wins (in the pool) were important but the performances were important as well. I think we achieved all the levels we needed to in those games.
"Where we were in the pool stages is the minimum, that's the bottom line, and we can only accept performances above that now."
D'Arcy had won his previous six Tests against Wales before last March's reversal in Cardiff. Warren Gatland's side are purring along nicely and boast a number of attacking threats.
"They've quality players across the board. There's a bit of familiarity between the teams, we know how to play against them, they know how to play against us. The results kind go either way every now and then," added D'Arcy.
"I don't think there's going to be a huge amount in this. But we're good at playing against Wales, we know we are. We just have to get things right on the money.
"They've got plenty of talented players, a lot of ball-carrying backs. I'm going to have a busy day tackling, but I'd do a thousand tackles if I have to."
GORDON D'ARCY AND BRIAN O'DRISCOLL'S WORLD RECORD RUN AS IRELAND'S STARTING CENTRES:
46 MATCHES - 31 WINS - 15 DEFEATS
February 22, 2004 - Six Nations - Ireland 36 Wales 15, Lansdowne Road (O'Driscoll 2 tries)
March 6, 2004 - Six Nations - England 13 Ireland 19, Twickenham
March 20, 2004 - Six Nations - Ireland 19 Italy 3, Lansdowne Road (O'Driscoll 1 try)
March 27, 2004 - Six Nations - Ireland 37 Scotland 16, Lansdowne Road (D'Arcy 2 tries)
June 12, 2004 - Summer Tour - South Africa 31 Ireland 17, Vodacom Park
February 6, 2005 - Six Nations - Italy 17 Ireland 28, Stadio Flaminio
February 4, 2006 - Six Nations - Ireland 26 Italy 16, Lansdowne Road
February 11, 2006 - Six Nations - France 43 Ireland 31, Stade de France (D'Arcy 1 try)
February 26, 2006 - Six Nations - Ireland 31 Wales 5, Lansdowne Road
March 11, 2006 - Six Nations - Ireland 15 Scotland 9, Lansdowne Road
March 18, 2006 - Six Nations - England 24 Ireland 28, Twickenham
June 10, 2006 - Summer Tour - New Zealand 34 Ireland 23, Waikato Stadium (O'Driscoll 1 try)
June 17, 2006 - Summer Tour - New Zealand 27 Ireland 17, Eden Park
June 24, 2006 - Summer Tour - Australia 37 Ireland 15, Subiaco Oval
November 11, 2006 - Autumn Test - Ireland 32 South Africa 15, Lansdowne Road
November 19, 2006 - Autumn Test - Ireland 21 Australia 6, Lansdowne Road
February 4, 2007 - Six Nations - Wales 9 Ireland 19, Millennium Stadium (O'Driscoll 1 try)
February 24, 2007 - Six Nations - Ireland 43 England 13, Croke Park
March 10, 2007 - Six Nations - Scotland 18 Ireland 19, Murrayfield
March 17, 2007 - Six Nations - Italy 24 Ireland 51, Stadio Flaminio (D'Arcy 1 try)
September 9, 2007 - Rugby World Cup Pool D - Ireland 32 Namibia 17, Stade Chaban-Delmas (O'Driscoll 1 try)
September 15, 2007 - Rugby World Cup Pool D - Ireland 14 Georgia 10, Stade Chaban-Delmas
September 21, 2007 - Rugby World Cup Pool D - France 25 Ireland 3, Stade de France
September 30, 2007 - Rugby World Cup Pool D - Ireland 15 Argentina 30, Parc des Princes (O'Driscoll 1 try)
February 2, 2008 - Six Nations - Ireland 16 Italy 11, Croke Park
March 14, 2009 - Six Nations - Scotland 15 Ireland 22, Murrayfield
March 21, 2009 - Six Nations - Wales 15 Ireland 17, Millennium Stadium (O'Driscoll 1 try)
November 21, 2009 - Autumn Test - Ireland 41 Fiji 6, the RDS (O'Driscoll 1 try)
February 6, 2010 - Six Nations - Ireland 29 Italy 11, Croke Park
February 13, 2010 - Six Nations - France 33 Ireland 10, Stade de France
February 27, 2010 - Six Nations - England 16 Ireland 20, Twickenham
March 13, 2010 - Six Nations - Ireland 27 Wales 12, Croke Park
March 20, 2010 - Six Nations - Ireland 20 Scotland 23, Croke Park (O'Driscoll 1 try)
June 12, 2010 - Summer Tour - New Zealand 66 Ireland 28, Stadium Taranaki (D'Arcy 1 try)
November 6, 2010 - Autumn Tour - Ireland 21 South Africa 23, Aviva Stadium
November 20, 2010 - Autumn Tour - Ireland 18 New Zealand 38, Aviva Stadium (O'Driscoll 1 try)
November 28, 2010 - Autumn Tour - Ireland 29 Argentina 9, Aviva Stadium (D'Arcy 1 try)
February 5, 2011 - Six Nations - Italy 11 Ireland 13, Stadio Flaminio (O'Driscoll 1 try)
February 13, 2011 - Six Nations - Ireland 22 France 25, Aviva Stadium
February 27, 2011 - Six Nations - Scotland 18 Ireland 31, Murrayfield
March 12, 2011 - Six Nations - Wales 19 Ireland 13, Millennium Stadium (O'Driscoll 1 try)
March 19, 2011 - Six Nations - Ireland 24 England 8, Aviva Stadium (O'Driscoll 1 try)
August 20, 2011 - Rugby World Cup Warm-Up - Ireland 22 France 26, Aviva Stadium
September 11, 2011 - Rugby World Cup Pool C - Ireland 22 USA 10, Stadium Taranaki
September 17, 2011 - Rugby World Cup Pool C - Ireland 15 Australia 6, Eden Park
October 2, 2011 - Rugby World Cup Pool C - Ireland 36 Italy 6, Otago Stadium (O'Driscoll 1 try)
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