These sides have faced off in two Grand Slam deciders in recent years, but even they pale into insignificance compared to this clash.
Ireland – who have never made it beyond the quarter finals at a World Cup – face a Welsh side looking to make the last four since the first time since the inaugural tournament in 1987.
While Wales have slipped under the radar somewhat with their easy progress to the knockout stages, Ireland have been one of the stories of the tournament following their rapturously received victory over Australia.
Those differences shouldn’t disguise the fact that both teams are brimming with confidence and both teams expect to win…
Ireland head into this game as narrow favourites at 4/6 with Wales out at 11/8 to progress to the last four.
It promises to be as tight as the odds suggest with the previous four games between these sides yielding two wins apiece.
However, Wales look in better shape than they ever have and face an Ireland team with an average age of more than 28.
With the likes of Sam Warburton, Shane Williams and Leigh Halfpenny starting and quality replacements like James Hook waiting in the wings, Wales may have enough to stop Ireland from reaching their first ever semi final.
The average points difference between the teams in the previous four games is just over six – and it’s only that high because of a 15 point victory for Ireland in 2010.
Ireland were comfortable in their final Pool C games against Russia and Italy, but Wales were absolutely ruthless in their comprehensive wins against Namibia and Fiji that saw them concede just seven points over the two fixtures.
Backing Wales with a three point handicap at 15/8 could yield a very tidy pay out.