Ireland easily beat Scotland 28-6 last Sunday, finishing the match particularly strongly after their influential lock was struck down with a chest infection on the eve of the game.
D'Arcy, who was rested after suffering illness earlier last week, comes in for Ulster's Luke Marshall to add more experience to the backline as they face a Welsh side bidding for a third championship in a row.
"It's pretty hard to pinpoint a weakness, man to man they're a very, very big side," Schmidt told a news conference of Saturday's opponents who beat Italy 23-15 in their opener and who also welcome back their captain, Sam Warburton.
"If you try to go through them, you're not going to get a lot of success so we're going to have be fairly smart about the way we play."
Saturday's game will also be the first time D'Arcy's centre partner Brian O'Driscoll will come up against Warren Gatland since the Welsh coach controversially dropped him from the side for the British and Irish Lions' third test against Australia last year.
The decision drew an angry reaction in Ireland, whom Gatland coached more than a decade ago, but O'Driscoll and his team mates have been keen to keep the emphasis on Saturday's game, which their captain predicts will be extremely tight.
"One of the big things Joe goes on about is a lot of these big games being one score games so between discipline, being accurate and defending well, you've a lot of opportunities to make up that one score, those games we lost last season." O'Connell said.
"If we repeat last year's performance we'll be very happy," O'Connell added, referring to Ireland's performance in Cardiff, their only victory of last year's championship.
Team:
15-Rob Kearney, 14-Andrew Trimble, 13-Brian O'Driscoll, 12-Gordon D'Arcy, 11-Dave Kearney, 10-Johnny Sexton, 9-Conor Murray, 8-Jamie Heaslip, 7-Chris Henry, 6-Peter O'Mahony, 5-Paul O'Connell (captain), 4-Devin Toner, 3-Mike Ross, 2-Rory Best, 1-Cian Healy
Replacements: 16-Sean Cronin, 17-Jack McGrath, 18-Martin Moore, 19-Dan Tuohy, 20-Tommy O'Donnell, 21-Isaac Boss, 22-Paddy Jackson, 23-Fergus McFadden.
(Reporting by Padraic Halpin; editing by Josh Reich)
