Irish rugby legend Paul O'Connell's hopes his memories of this World Cup will be happier than his final one as a player in 2015 when Ireland once again failed to get past the quarter-finals.

The 43-year-old Irish scrum coach was captain of a star-studded side that beat France in the pool stages in a victory but suffered injuries to several key players, including O'Connell.

Johnny Sexton, another of those who failed to play in the quarter-final where they were whipped 43-20 by Argentina, captains the present team which O'Connell believes is "better" than the 2015 vintage.

Sexton, 38, is expected to make his first competitive appearance since injuring his groin in the win over England in March that sealed the Grand Slam, in Ireland's opening pool match with Romania in Bordeaux on Saturday.

The talismanic fly-half hopes to set the seal on a magnificent career by lifting the Webb-Ellis trophy on October 28, or at the very least become the captain of the first Irish side to reach the semi-finals.

"This is a better team," said O'Connell on Tuesday.

“Physically, a lot of us were incredibly committed but these guys -– there's some serious athletes in the team, particularly in the forward pack.

"Guys that can accelerate quickly, they can change direction really quick."

- 'Different World Cup' -

The former Munster star, capped 108 times, says the present generation seem to be sharper than their predecessors in taking new ideas on board.

"We've players that are able to figure things out really quickly," said O'Connell.

"We can come up with something and they will adapt it to their game quickly.

"That's the biggest thing I've found since I've come back into the Irish set-up two years ago, the smarts of the players is a real strength of theirs.

"So, I think they're further down the track than any Irish team I played in, for sure."

Two of O'Connell's key players in the scrum will not make the Romania match -- hooker Dan Sheahan has a sprained ligament in his foot and back row forward Jack Conan has a foot injury.

However, he is confident they should be fit for the second pool match a week later against Tonga in Nantes.

O'Connell will want them match fit then as their two toughest matches come afterwards, against defending champions South Africa on September 23 and Scotland on October 7, both at the Stade de France.     

Sexton for his part is comforted by O'Connell's presence in the coaching set-up under Andy Farrell.

"I think the advantage of having the coaches involved in the last one and Paulie being there as a player, is that they know what works but the proof is in the pudding," said Sexton after the Irish settled in to their training camp last Saturday.

"When we get out and play, that will determine how good our prep has been.

"So it's all to do, it’s all in front of us."

Sexton says his experiences at previous World Cups mean little as he enters his fourth and final one.

"I probably learned something at all of them but they’re all different," said Sexton, who will hang up his boots once Ireland's campaign is over.

"Each one, I learned different things along the way and this will be another different World Cup.

"It's probably why it's hard to get them right, you know, very rarely do you have the same carry-over of players' experiences."

Sexton says the historic series win in New Zealand and the Grand Slam this year mean a lot but it is the World Cup they have been building for for four years.

"It gives us a little bit of confidence that you've got that body of work that you've built well over the last four years but it was all to get us to this moment," said Sexton.

"Those things will never get taken away from us -- the wins in New Zealand, the Grand Slam -- but it was always with the World Cup in mind."

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