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The Rugby World Cup has come at just the right time for Ireland as they prepare for a future without Paul O'Connell, says Shane Horgan.

The lock has decided to retire from the international game after the tournament and Brian O'Driscoll has not long quit as one of the team's long-standing stars.

But Ireland's rebuilding is well under way and there are key senior players who should reach their peak during the event. Despite a disappointing club season for Irish teams dampening expectations, Horgan said the changing of the guard may work in favour of Joe Schmidt's side.

"There's a mixed mood around Ireland rugby at the moment," Horgan said, reflecting on successive Six Nations titles. "The national team has done so well over the last two years and transitioned a lot of new players during that time.

"It [the team] has developed real depth. Robbie Henshaw, Jack McGrath, Jordi Murphy, Tommy O'Donnell and Iain Henderson have all been brought in, which is a real positive from an Irish perspective.

"In some ways, this World Cup has come at the right time. That was our big concern -- how we were going to fill that gap left by Brian. You'll never replace Brian, but you've given the players that have come in a bit of lead time to this World Cup.

"We've got a lot of players back from injury, too. You've got a core group that I believe will be playing at their peak -- [Jonathan] Sexton's probably going to be at his best and so should Sean O'Brien.

"Then you've got O'Connell in what will be his farewell. You've got a lot of players in this team who should be playing at their optimum level at this World Cup -- they'll need to do that to have any chance."

Following a favourable pool draw, reaching the semifinals for the first time in Ireland's is a realistic possibility. However, after seeing the provinces suffer both domestically and in Europe last season, Horgan warned of the potential effect on Schmidt's squad.

"[It was] a disappointing last season for all of the provinces," the Heineken ambassador said. "Ulster probably thought it would be their best chance to win the Guinness PRO12, but went out in the semifinals. Munster had a really bad European campaign for the first time in a long time and were roundly beaten in the PRO12 final.

Ireland wing Shane Horgan looks dejected after the final whistle against Argentina at the 2007 Rugby World Cup© David Davies / PA Archive/PA Images

"Leinster were poor all over and endured probably their worst year in however long, losing their coach as a result. That will dampen some of the expectations going into the World Cup, because there is still a connection between what players are doing week in, week out and what they're doing at a national level."

As a player, Horgan endured mixed World Cup campaigns with Ireland. The former Lions wing has fond memories of his part in the 2003 team that reached the quarterfinals in Australia; less so the disastrous 2007 outing in France when Eddie O'Sullivan's charges failed to make it out of their pool.

"We went away in 2003 to Australia and it was one of the best experiences we've ever had. Ireland had a brilliant base and it was great fun; everyone was relaxed and calm. It was probably the best tour I've ever been on," Horgan said.

"We then went to France with huge expectations. We stayed at a hotel that wasn't finished in time in Bordeaux. We were collectively nervous about our performances, we didn't have that time to unwind, relax and take it easy. Our performances reflected that.

"What happened with the hotel, you don't even recognise you're going through it while you're there -- having somewhere settled just makes things easier. The guys are happier and they don't have the world on their shoulders.

"All you want to do is facilitate players to play as well as they can and the main thing behind a player playing well is if they're happy or not.

"There are very fine margins -- one of those is the mental state of things. How much are you enjoying being part of a World Cup? The teams that you see that are actively enjoying a World Cup -- Australia are great at that -- are often the ones who perform very well."