The Ireland captain -- who had been nursing an ankle injury -- will start alongside Fergus McFadden in the centre after D'Arcy's rib injury did not clear up in time for today's meeting with the newcomers to European rugby's top tier Exeter Chiefs at the RDS (3.40).
The New Zealander has sacrificed a back on his bench to name two back-rows, Jordi Murphy and Leo Auva'a as cover, in case the 27-year-old's arm injury flares up again.
Leo Cullen and Cian Healy return in the only changes from last Saturday's win over Munster and O'Driscoll (below) admits that all of the pressure sits on the shoulders of the holders against the Devon side today.
"No disrespect to Exeter, it would be a surprise if they qualified, but they have every capability of beating the other teams at some stage in the competition too," he said.
"They're a good team. A very good team. And they're very much that -- a team.
"They mightn't have that many galacticos but they have a real team mentality and they play very hard for one another."
"They've nothing to lose when they come over to play us in the first game -- (we're) reigning champions and it is their inaugural season in the Heineken Cup. They'll be licking their lips."
Meanwhile, Munster will not have to contend with Argentina fly-half Juan Martin Hernandez at the Stade de France this afternoon.
The Racing Metro pivot suffered an injury playing in his country's final Rugby Championship defeat to Australia last weekend, and English No 10 Olly Barkley makes his first start in his place after joining from Bath.