Johnny Sexton has admitted that part of him "hated" playing for Ireland when his rivalry with Ronan O'Gara was at its most intense.
Sexton will fly out to Japan tomorrow with the Irish team to take part in his third World Cup, but the showpiece tournament hasn't produced great memories for the current World Rugby Player of the Year.
Ireland exited at the quarter-final stage in both 2011 and 2015, with Sexton not starting either game.
He missed out through injury four years ago as Ireland were thumped by Argentina in Cardiff, while Declan Kidney opted to start Ronan O'Gara against Wales in 2011, with Sexton selected on the bench.
That period was dominated by Sexton versus O'Gara talk, with Kidney often changing his mind on who his first-choice out-half was.
Sexton got the nod for the crucial pool stage clash against Australia in New Zealand, where Ireland recorded a famous win, and speaking to Off The Ball on Newstalk, the number ten admitted that he felt huge pressure during the game with the shadow of O'Gara looming large.
"It was the highest pressure I'd ever felt for a kick, and I nailed it," Sexton said of a penalty attempt as O'Gara was preparing to come in.
"I got another kick out towards the sideline, took it on, a great kick but it hits the post. I thought it was over the whole way.
"That's sport, ROG came on, kicked a couple of good kicks and he retained his place for the Italian game and the quarters."
Sexton also admitted that he didn't enjoy playing international rugby at the time, but admits now that it was a valuable learning experience.
"It was crazy, part of me hated playing for Ireland," Sexton admitted.
"You feel like half of the country is against you and you are playing for Ireland and doing something you've dreamt of since you were a kid.
"You think that when you play for Ireland that you'll have the full support of the country, but that was wishful thinking.
There was a lot of criticism because ROG was such a great servant for Irish rugby. It made it difficult."
"I learned so much from that campaign," he added.