Despite having a paltry share of possession, Ireland soaked up all the Welsh pressure as they sneaked ahead with an early try through hooker Rory Best before Captain Brian O'Driscoll touched down just before the end of the first half. With time running out and the score delicately poised at 12-9, fly-half Ronan O'Gara poached a late try to give them a 10 point win.
"Experience was the big factor," said O'Sullivan. "We made mistakes around the breakdown which can be fixed easily, but you can't quickly teach what to do under pressure or coach it in a few sessions.
"It was pleasing to score three tries and our defence was excellent, it wasn't a vintage display, but you never come to Cardiff and have an easy win. You have to give some credit to Wales, they will be disappointed not to get something from the game.
"We won't get carried away with that result, if we play like that against France we will get punished, but I am reasonably pleased with our first game of the tournament."