The passing of France’s Imanol Harinordoquy will be critical when Les Blues take on Nick Easter and England in the second of Saturday’s two Rugby World Cup quarterfinals. (Peter Parks/Christophe Simon/AFP/Getty Images)

It’s time for the big boys to battle it out for the Cup.

Rugby’s thoroughbreds are all that remain with the quarterfinals set to get underway Saturday night (before dawn in the U.S.). The hosts (New Zealand), defending champions (South Africa), Tri Nations champions (Australia) and most of the British Isles makeup a heavyweight slate of matchups that should make for a riveting weekend of rugby.

Here’s a quick look at each of the four quarterfinal pairings...

Ireland vs. Wales

Sat., 1 a.m. EST in Wellington

An all-Celtic clash pits two teams looking to make history on the sport’s grandest stage. The Welsh have not reached the semifinals since the inaugural 1987 tournament and the Irish have never advanced beyond the quarterfinals.

Ireland’s upset of Australia in Pool C showcased their grit, which is an apt description for the trio of No. 8 Jamie Heaslip and Stephen Ferris and Sean O’Brien on the back row.

With an average age of 25, Wales has been one of the pleasant surprises of the tournament. They nearly knocked off the defending champions in their opener against South Africa and closed strong with a pair of convincing blowouts of Namibia and Fiji. Rhys Priestland’s passing has been key to the team’s attack, and the team has dangerous quick-strike ability.

2011 Rugby World Cup photo gallery

England vs. France

Sat., 3:30 a.m. EST in Auckland

Despite advancing as the top team from Pool B, England has failed to inspire so far in the tournament. They narrowly edged Argentina 13-9 in their opener then had to come from behind to beat Scotland 16-12 in their finale. It’s fair to say the team could use a spark, which is why manager Martin Johnson selected Toby Flood, Nick Easter and Tom Palmer for Saturday’s quarterfinal. Flood has played well against the French in the past and his inclusion should bolster the midfield.

The French defense was victimized for 96 points in pool matches, including nine tries, and trailed for 136 of 320 minutes in the tournament. That won’t do against an English side that will look to get out in front early and force Les Blues to recall semifinal defeats in 2007 and 2003. The French desperately need to improve their tackling on Saturday and hope they can continue to capitalize their place kicks — they lead the tournament with an 85 percent conversion rate on 26 attempts.

Here’s a retrospective of the ‘03 and ‘07 matchups on The Guardian.

South Africa vs. Australia

Sun., 1 a.m. EST in Wellington

The Springboks haven’t been in peak form so far, surviving a one-point squeaker over Wales in their opener, and capping their first-place finish in the toughest pool at the competition with a narrow 13-5 victory against Samoa. last week. The Wallabies, meanwhile, finished second in Pool C after losing to Ireland in a match that saw their scrum overpowered. In their Tri Nations victory earlier this year the Aussies exposed 33-year-old South African captain John Smit, and they’ll go after the hooker again on Sunday.

South Africa's Springbok John Smit (L) doesn’t have the legs he once did and Stephen Moore and Australia will be looking to exploit the 33-year-old to topple the defending champions. (STF/AFP/Getty Images)

New Zealand vs. Argentina

Sun., 3:30 a.m. EST in Auckland

The host All Blacks ran roughshod over their pool opponents to the tune of a 240-49 scoring margin despite a number of lineup changes forced by injuries. They shouldn’t have too much trouble with an overmatched Argentina side, setting up a tantalizing Tri Nations semifinal matchup with either the Springboks or Wallabies. But the home crowd at Eden Park will be looking for another lopsided victory to allay fears that the Kiwis could struggle without flyhalf Dan Carter who has been ruled out of the tournament with a groin injury.

Carter owns an international record 1,250 test points and is widely regarded as the best No. 10 in the world — leaving large shoes to fill for Colin Slade. But former All Blacks captain Tana Umaga isn’t worried. Here’s his take from a Saturday morning post on the New Zealand Herald’s website:

Slade has the chance to show his skills in this quarter-final. I believe he will do well. If he settles, feels happy and just worries about his areas and understands what his role is, the rest will fall into place. Slade has plenty of strengths to his game and he will get support from those guys around him who are very experienced.”