Ronan O' Gara: Age 32, Position Out'Half Heineken Cup Points 1034

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Felipe Contepomi: Age 31 Position Out-half Heineken Cup Points 418

Without the ball, the two rival playmakers won't be able to work their different brands of magic, so while the game begins and ends with the confrontation up front, there is still every reason to believe that the match-up between the number 10s will be a major factor.

If Contepomi has had his good days against Munster in the past, it's impossible to forget the way he imploded during the 2006 semi-final. Donncha O'Callaghan, Denis Leamy and even O'Gara himself, to a lesser extent, managed to get into the Argentine's head with devastating results for Leinster.

And there were shades of Contepomi's fragile temperament in both Magners League games this season. His place-kicking failures at Thomond Park meant that, critically, Leinster were never able to get a foothold, and while Munster might have won anyway, his misses contributed hugely to his team's demise.

For all his undoubted talent, Contepomi has not had a good final season for the province, and another defeat by Munster at this stage of the Heineken Cup would be a bitterly disappointing way to bow out for a player who has given much to the cause over the years.

Although O'Gara has carved out his own place in Irish rugby history with his dramatic last-ditch drop goal in Cardiff, it's not as if he produced a series of vintage performances in the Six Nations. His kicking, both from the ground and from the hand, was mixed by his high standards, and he is not in Contepomi's league as a defender.

But his form for Munster has been imperious, and his confidence is as high as it's ever been in his career. While Leinster are hoping that Contepomi will kick his goals and keep his cool, Munster are presuming that O'Gara will lead them to victory.

John Hayes: Age 35 Position Tight-head prop Weight 19st 9lbs

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Cian Healy: Age 21 Position Loose-head prop Weight 17st 4lbs

Even though Hayes has never forged a reputation for himself as a destructive scrummager, the veteran tight-head will be looking for a bit of retribution next Saturday. He might have 86 Heineken Cup appearances in the bank as against Healy's nine, and he might be playing in his eighth semi-final, but all that didn't count for much when the 35-year-old was shunted around by the rookie at Thomond Park recently.

In fact, Hayes's struggle to contain the hugely promising Healy that day might even have impacted on his Lions prospects. He is regarded as one of the game's supreme line-out lifters and he has been impressively consistent this season, but that scrummaging blip was one that he and Munster mightn't have seen coming.

Forewarned is forearmed, and it's unlikely that Healy will have the edge this time, but if he happens to disrupt the rock on which Munster have built their scrum, then Leinster have the added advantage of making life more difficult for whichever of David Wallace and Denis Leamy is picking from the number eight slot.

While the 21-year-old has been learning his trade in the tight, he has mostly impressed as a highly explosive ball-carrier. With World Cup-winner CJ van der Linde in the squad, and with Stan Wright having a good season, he mightn't have expected so much Heineken Cup game time, but the South African's recurring foot injury has given Healy an opportunity which he has managed to grab.

Another big performance on Saturday will put him in the frame to bump Marcus Horan out of the Ireland side next season. But with the stakes as high as they are, Hayes and the rest of the Munster forwards might have other ideas.

Keith Earls: Age 21 Position Outside centre Heineken Cup Appearances 7

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Brian O' Driscoll: age 30 Position Outside centre Heineken Cup Appearances 58

Turn back the clock, and there is much about Earls with his power, anticipation and quick feet that remind you of a young O'Driscoll. When he first burst onto the scene, O'Driscoll wasn't much of a defender, whereas now, he's a grand master of the art, and he knows he's bound to have his hands full at Croke Park.

Earls possesses the blistering pace his Ireland captain now lacks, and while he would've been hanging on O'Driscoll's every word at international squad sessions, this is his first opportunity to go head-to-head with someone who could write the book on midfield play.

It's akin to the sort of challenge Earls will be facing with the Lions in a few weeks time. If he can achieve parity with O'Driscoll, then you feel that he'll be able to cope with whatever is thrown at him in South Africa.

Earlier in his career, O'Driscoll would have finished off that kick-and-gather chance he created for himself during the second half against Harlequins. When he was tracked down in a marvellous double-tackle by Ugo Monye and Dave Strettle, you had to wonder whether the Quins defenders were as frighteningly quick as they looked, or whether O'Driscoll had definitely lost that turbo charge. Probably six of one.

Those tightened hamstrings might be cramping his style in attack, but his contribution to Leinster's rearguard action at the Stoop was magnificent. No one will perform next Saturday with as little regard for his physical well-being as O'Driscoll, and no one will be more determined to justify his Lions place than Earls.

Of the micro contests in the mother all Irish rugby battles, it might just be the most fascinating of all.