Former Ireland captain Brian O'Driscoll knows the pain of Rugby World Cup exits, and he understands how difficult it will be for Johnny Sexton to come to terms with Ireland's 28-24 defeat by New Zealand on Saturday.

O'Driscoll was skipper when Ireland lost to Wales at the quarterfinal stage of the 2011 World Cup, when current captain Sexton was also part of the team, and both players have taken part in four World Cups without reaching the last four.

"It's tough when you don't get that fairytale ending you were hoping for," O'Driscoll said on ITV. "In many ways, his life could have been mapped out with a different result if he was into a semifinal."

In the final minutes, Ireland hammered away at the All Blacks line, but New Zealand held out.

"They threw everything at the All Blacks. You can always looked back at missed opportunities, but they gave everything they had and they were repelled," O'Driscoll said.

"There is nothing between the sides. A score at the other end and you could have no argument about Ireland nicking it. That is the fine margins."

O'Driscoll believes it could have been a different story.

"The really frustrating thing, and talking about Johnny Sexton looking back we have to say it, there was a missed penalty after 58 minutes that gets it to within drop goal range. That's what makes it all the more painful.

"If you are pulling it apart and splitting hairs, the reality is that they had to score a try and against a resolute defence like that with very tired bodies at the end of the game, it was always going to be a big ask.

"I'm sure Johnny will potentially look back on that and really kick himself. You never blame kickers but knowing him, it will be one that will really hurt him."