Donal Lenihan says Irish rugby can forget about making an impact at the World Cup if "born leader" Peter O'Mahony is allowed to leave.

The Munster captain said today that he's "hopeful" of striking a deal with the IRFU amid reported interest from French and English clubs for his services.

Simon Zebo is destined for Racing 92 next summer, while Donnacha Ryan is already in situ. But it's O'Mahony's departure that would leave the biggest void according to the RTÉ Rugby analyst.

"The signs at the moment aren't great," he told RTÉ 2fm's Game On.

"It's the last thing Johann van Graan would want, just coming into this first Champions Cup game.

"To have that distraction isn't great but it's inevitable these things are going to happen more and more. We've spoken in the past about the increased TV rights and the money that's in France now.

"It would be a disaster if he were to leave Munster. You go back to 2015, everybody knows what happened in the (World Cup) quarter-final against Argentina. We got a number of injuries and we didn't have the strength in depth to deal with that.

"I think if Peter O'Mahony, born and raised in the province with Munster DNA in his blood, if somebody of that ilk was to leave, it would be a massive blow to Munster rugby"

"Ireland's minimum aspiration going into the next World Cup has to be to make the semi-finals and hopefully go on to reach a final. You won't do that unless you have all of your quality players available.

Peter O'Mahony is one of those. He's a born leader, a very influential figure.

"I see Peter O'Mahony very much as a starter for Ireland and even more integral to Munster. Having lost Donnacha Ryan and Simon Zeb, I think if Peter O'Mahony, born and raised in the province with Munster DNA in his blood, if somebody of that ilk was to leave, it would be a massive blow to Munster rugby."

Van Graan gets his first taste of European action in the Thomond Park dugout this weekend when Leicester Tigers come to town.

Aside from the mutterings about O'Mahony's future, the South African has also had to deal with a stack of injuries. Preparation has been rocky, but Lenihan says they can take massive comfort from being on home soil.

"Having the first game up against Leicester in Thomond Park will be a huge boost.

"Given the background they've had with all the injuries and the fact they have;t played together since the end of October because of the November series, I think it's just as well that the first of the back-to-back games is in Limerick."

"It's all very well saying there are a lot of back-row options out there, which there are, but some of them are far less experienced than others.

"You also want to have a minimum of two top-quality internationals for every position on the field. Back-row itself is an area where the attrition levels are always huge.

Listen to exclusive Champions Cup radio commentary of Exeter v Leinster on RTÉ Radio One’s Sunday Sport programme (kick-off 5.30pm).

Live updates of Munster v Leicester on Saturday (7.35pm) and Sunday’s games featuring Harlequins v Ulster (1pm) and Exeter v Leinster (5.30pm) on RTÉ.ie and the News Now app.