O'Driscoll's failure to recover from his hamstring injury in time for the Paris showdown sees his provincial team-mate fill the number 13 shirt - although for D'Arcy the position is of little importance.
"A starting place in the Ireland team is everything I've worked for. I couldn't care less what position it is, as long as I play," said the 24-year-old, who has already won five caps as a substitute.
"It's a great compliment from (coach) Eddie O'Sullivan that he has the confidence in me to replace the best centre in the world. There are similarities between Brian and I - we're the same size and same build and we're both good broken field runners."
However D'Arcy, who played hooker until he was 15 - "my coach was sick of me never going into any rucks, so he told me that if I wanted to run like a back I could be one" - admits he will relish his midfield duties.
"I'm looking forward to the match and playing centre. Your mind doesn't have time to wander when you're at centre - you have to concentrate the whole time, which suits me. I like the fact that I get more ball and have a chance to run at people.
"I've spoken to Brian. He told me to be patient and it will come. It's hard for him that he can't play - it's a bitter pill to swallow having to watch the game. But he's been very helpful since I found out I was playing."