Irish rugby's biggest provincial fixture takes place this Saturday with Leinster travelling to Thomond Park.

Both teams are much changed at fly-half since their last meeting. Jonny Sexton has left Leinster for France, while Ronan O'Gara has retired for Munster.

Keith Wood and Gerry Thornley joined Ger last night to preview the game and look at the choices at No 10.

Conor Murray may return from injury in time to play some part against Leinster and Thornley believes this is vital in the immediate post-O'Gara era.

"When you lose a player like Ronan O'Gara and you've got two comparatively callow, inexperienced out-halves vying to inherit such an iconic jersey, then all the better that you have a very experienced scrum half in the inside. Leinster have that in Reddan and Boss," said Thornley.

It looks like Ian Keatley will be given the nod to start at out-half for Munster, with JJ Hanrahan expected to push him for the jersey.

Wood thinks Rob Penney has made the right call:

"I don't know if it's pure anointment but he should be the man with the jersey. It really is the chance and the opportunity for Keatley to go on and make it his own. It is the opportunity for Hanrahan to attack that when he gets the chance. While Munster have scored some good tries so far this season, at times I think they need to have more command at 10 to take control. Last week they kept doing this one phase thing which was a little bit annoying. But I think Keatley is more comfortable with it, is older and has more maturity."    

Leinster also have question marks at 10 with Ian Madigan and New Zealander Jimmy Gopperth to choose from. Thornley has a hunch that Leinster head coach Matt O'Connor will plump for Gopperth.

"I've got a hunch from listening to every word Matt O'Connor says: I think he's going to with Gopperth. When you're a new coach coming in to take over from Joe Schmidt, it's arguably the hardest act to follow. That's compounded by losing the No 1 out-half in Europe in Jonny Sexton. When choosing between an experienced man like Gopperth and Ian Madigan, I think he'll go for Gopperth because he's older and has been around the block. He also provides a running threat of his own. He also has that bit more experience managing games at 10.

Jimmy Gopperth and Ian Madigan ©INPHO/Dan Sheridan

"It would be very unfortunate, unfair and very harsh on Madigan as he has done nothing wrong. His ability to locate the try line is remarkable. I just feel in terms of that experience and game management, O'Connor might go for Gopperth."

Wood was blunt when he said that he did not like that proposition. But he and Thornley have backed Leinster to come out on top, with Brian O'Driscoll a key figure.

"I think O'Driscoll being dropped for the third test of the Lions was possibly the biggest disappointment of his career, but the biggest boon for Leinster and Ireland because he looks like a man on a mission, judging by the way he hit the ground running last week. Leinster and Ireland will feel the benefit," said Thornley.

Wood and Thornley also discussed the possible effects of new scrum laws and contract situations.

Leinster and Ireland pair Sean O'Brien and Jamie Heaslip could move to the Top 14 in the future if their contracts situations are not resolved but Wood fears for O'Brien more than Heaslip if he makes that move.

"I would hope that we look after a guy who has a good few miles on the clock and is prone to having some injuries. The IRFU should make a very strong offer for him so that he can play the rest of his career in Ireland, earning a good wage and more importantly not playing as many games as he would invariably have to. I wouldn't worry about Jamie Heaslip because he's pretty much bulletproof."

Munster's Ian Keatley scores a try despite Leinster's Dave Kearney ©INPHO/Billy Stickland