The Leinster centre will make his full debut in the RBS 6 Nations opener against France but his delight will have been tempered by the challenge of filling the shoes of Brian O'Driscoll, one of the game's biggest talents.
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."