And perhaps the selection that raised most eye-brows among the assembled media was the pairing of Gordon D'Arcy and Brian O'Driscoll in the centre, with D'Arcy set to wear the number 13 jersey.
"I thought Gordon did well last week at outside centre and Brian is back again fit so I think it's a slightly different angle on the midfield having two similar type ball players there who'd be different type game breakers than Kevin Maggs, more elusive and more capable of distributing as well in different parts of the field." O'Sullivan explained. "A question really of putting an extra play maker into the backline."
Was there an element of taking the Welsh at in their own game with this selection ?
"No not really, what I'm doing is trying to pick the team that will play the best game for us really. I know the Welsh are playing run n gun at the moment but we'll worry about that when they have the ball. The purpose for us when we have the ball is play our own style of game, it'd be similar to Wales I suppose but it's not any great sea-change to approach Wales differently because of the way they're playing."
"He took full part in training on Monday. He was a bit tired Tuesday and we didn't want to take any risks, so he did a half session and took a full part yesterday (Wed). As of now he's good to go."
" I think Brian is one of the best game-breakers in the world. His ability to get the ball over the gain line and make important yardage. He was that ability and he's a good finisher as well, his strike rate is pretty good. And anywhere he's on the field he gets huge respect from the opposition which often opens up space for other people. It's having him there is pretty important, never felt otherwise about it. It's good to have him back."
It was a tough call O'Sullivan admitted, to leave out Malcolm O'Kelly for Donncha O'Callaghan. "Yeh, tough call. Malcolm after all with 60 caps under his belt. I just felt a change again in tactics allows us adjust our line-out in terms of jumping Paul at 4 and Donncha at 2, whereas Paul was jumping at 2. I think Donncha did well around the field when he came on last week. So it was a tight enough call, it could have stayed the way it was but I think it spices it up a bit in the front five."
And what does O'Callghan bring to the party ?
"I think Donncha plays with a certain amount of abandon." O'Sullivan said.
"He throws his body around. He's a good line-out operator. He did a very good job during the World Cup off the bench for us and. It's a bit of a call picking him but I think he's ready for it. Having said that, if Malcolm has to come in I'm sure he won't leave anything behind him. It's a good dynamic to have between the three locks but. I think starting Donncha brings maybe another edge to it but we'll see, that has to happen yet, but that what the expectation is."
"They're all important games in the Six Nations, this is the tournament of the year, every year. Realistically we want to win our home games. If we win away from home in the Six Nations it's a big achievement as we saw. Very hard to win in Paris, very hard to win in Twickenham.
"This is our first home game and obviously we're targeting it to win. But we have to respect the fact that Wales have turned the corner in their game and they're a different side now to what they were 12 months ago. And even 12 months ago we just about got out of jail in Cardiff so I think Sunday is going to be pretty much a 50/50 game.
They've just picked up where they left off in Rugby World Cup. They've been playing a very expansive game. They have some very good game-breakers and they're getting the ball to them in broken play and they're creating a lot of problems for people.
"They've certainly got their work ethic right. There aren't really any stars in the team but they're all hard workers and they work for the 80 minutes. Y'know, if everyone works for 80 minutes and plays with a bit of passion, it's a pretty good cocktail to bring to a Six Nations game.
"Yes, it is an important game, there's no doubt about it. But we shouldn't have any belief that we have a divine right to beat Wales cause we've had it over them for the last few years. To do that, we're going to have to play very well. If we don't we'll come out the wrong side of the game."