"I did a reccie back in April to look at the facilities and the most impressive thing that happened when I got there was when we sat down with the stadium director Peter McKenna.
"He said: 'Now that you're going to play at Croke Park, you have to realise that this is your home ground every time you're here. Anything you need to do the job, we'll get it done for you.'
"At the same time, one of the most important things for us is to forget about Croke Park for the moment.
"If we don't do that before we go to Cardiff, we're asking for a root in the backside."
A win against Wales next Sunday would set O'Sullivan's charges up nicely for February 11's historic home meeting with France, and whilst admitting that the players' focus is totally on Cardiff, the Corkman did give his thoughts on the playing surface at Croke Park.
"We trained on it twice last week and it was fine. It was very firm but it can take a stud. I would compare it to the Stade de France pitch. It's very similar," he said.
"The floodlights are excellent also. It's a great pitch and I'm very happy with it."