You think of combinations in Irish rugby and immediately land on O'Callaghan-O'Connell, Reddan-Sexton and D'Arcy-O'Driscoll.
However, a relationship that tends to get overlooked but was, arguably, the most significant for Ireland in the Six Nations -- and will be at the World Cup -- is the one forged between Greg Feek and Mike Ross.
Former All Black Feek was brought in as Leinster scrum coach at the start of the season and then swiftly co-opted into the Ireland set-up for the November Internationals. And, even though Ross was not used in those four games, it was clear his bond with Feek was cementing.
The two self-professed scrummaging nerds could be seen in deep discourse around the squad hotel in Killiney, frequently on their feet to emphasise some shoulder angle or stance. That partnership has since flourished to the point where Ross is now the fulcrum of Ireland's scrummaging effort, and it has been an unexpected bonus for Feek.
"Yeah, it was 'Mike who?' back in August when he was mentioned to me," said the New Zealander. "He's come on well, Rossy -- I certainly know more about him now."
Feek's work with his Leinster and Ireland colleague Cian Healy is also reaping rich rewards and, with Heinke van der Merwe and Stan Wright on their books, the scrum guru has the propping raw materials to put it up to most scrums in Europe -- and they'll need all the power they can muster against Leicester on Saturday.
The Tigers are an old-school outfit who have always prided themselves on their scrum and continue to do so under the guidance of former hooker Richard Cockerill. Even without their suspended Puma Marcos Ayerza at loose-head, Cockerill's men will be determined to set the tone at the primary point of contact and provide a platform for half-backs Ben Youngs and Toby Flood.
Cockerill has the option of starting Dan Cole or Martin Castrogiovanni at tight-head with Ayerza's solid, uncapped understudy Boris Stankovich on the far side. Alternatively, he could pick both internationals, with Castrogiovanni at loose-head, where the Italian has done a job in the past.
Whoever lines out, the scrum promises to be an intriguing contest in a quarter-final packed full of them, and there are plenty of individual motives to consider also. Healy did very well against Cole when Ireland stunned England last month but the English camp were reportedly incensed by the interpretations of Bryce Lawrence. Meanwhile, Healy had his own issues with referee Romain Poite when Castrogiovanni clearly scrummaged illegally for Italy in Rome.
Then there is Andrew Small's bizarre, and critical, penalty award against Leinster last weekend when Ross (below) was obviously in the ascendancy against Munster's Wian du Preez, who was replaced by Marcus Horan not long afterwards. Plenty of points to prove then, and, whichever scrum gets on top, one hopes that dominance will be recognised by referee Nigel Owens in what is another chance for Feek to demonstrate his value to Irish rugby.
"As coaches, you've got to be confident, believe in your guys and believe in what you're doing. They (players) need to believe in their own minds too and have everything technically right as well."
If Leinster get it right on Saturday, the Feek and Ross show might just begin to gain the attention it deserves.