McFadden is one of seven changes made by Ireland coach Joe Schmidt from the side that won the first Test 29-17, with Ulster's Darren Cave shifting to inside centre and team-mate Luke Marshall dropped from the squad.
McFadden, 27, has scored 287 points in 79 RaboDirect PRO12 appearances for Leinster with most of those coming on the wing, but he does know the centre role well having played there during his school days and on occasions for Matt O'Connor's side.
And after playing with O'Driscoll, who bowed out of the game in Leinster's RaboDirect PRO12 final victory over Glasgow Warriors, for his whole professional career, McFadden is ready for the near-impossible job of replacing him.
"There's always going to be hype in the media, saying 'who will be the person to grasp the jersey?' or 'who'll fill Brian's boots?'," he told the Belfast Telegraph.
"You guys know as well as I do that no one's going to fill Brian's boots, they're unfillable.
"There's an opportunity there at No.13 in an Ireland jersey and there are plenty of people who are looking to take it.
"But when you look at the injuries before the Six Nations, when guys got opportunities under Joe, one thing that he does is, if someone gets their hands on a jersey and they do a job there, he doesn't tend to pass it to someone else.
"I'm not too worried about what Brian has done there. The jersey's going to have to be worn by someone else and this is my chance."
While O'Driscoll saw the No.13 role as that of a centre forward in football, McFadden sees it as more of a midfield role and the most important position on the pitch.
"It's an interesting analogy about the centre forward - I think it's the fulcrum of the defence," he added.
"Obviously, you want your scrum to go well, you want your line-out to put pressure on defensively, but if you make bad reads ... like, if you miss a tackle in the front five, it gets wiped up by other people. If you miss a tackle at No.13, everyone knows about it.
"You're the person who gets pointed at the next day, there's a lot of pressure there. In that sense, it's the most important position on the pitch.
"From an attacking perspective, you're basically the link from No 10 and the outside players. You're the link who can bring some organisation into it."
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