Ireland have won their last five meetings with Argentina and should make the semi-finals.
The boys in green have defied adversity and tension to win the last two Six Nations titles. Head coach Joe Schmidt and his assistants will have noted the extra adventure that Argentina are playing with at the moment and come up with plans. The stand-ins are all of Test-proven quality and there is no shortage of leadership skills still in the team from number eight Jamie Heaslip through Sexton to full-back Rob Kearney.
Ireland had a tournament reality check when they could not roll over Italy two weeks ago and last Sunday, they may have only scored two tries but they played France off the pitch in their Pool D decider.
However, the Pumas are a different beast at World Cups and are worth a bet with a five-point start in Sunday's first quarter-final. They seriously worried New Zealand for an hour on the first Sunday of the tournament and have racked up try-bonus point wins over Georgia, Tonga and Namibia since. They are no longer reliant on smashing teams up front and goalkicking, with tries almost an after-thought.
Three times the teams have met in past World Cups with Argentina winning two and losing the third by a point. Eight years ago, Argentina finished third after beating hosts France and Ireland in the pool stages and Scotland in the quarter-finals before losing to eventual winners South Africa. Four years ago, after coming through a pool with England, the Pumas pushed the All Blacks so hard in their quarter-final that an injured Richie McCaw would not leave the pitch until the result was effectively confirmed.
The atmosphere in Cardiff should be cracking with Irish supporters already making the Millennium Stadium a second-home for two of their four matches and the Argentinian fans never shy to make their lesser numbers felt with noise. But this may not ease the early tension and a bet on under 19.5 points in the first-half at 4-5 is advised also.
In the second Sunday quarter-final at Twickenham, Scotland can stay within 16 points of Australia. They did at Murrayfield in November 2013 (21-16) and they stunned them 9-6 in the wet down in Newcastle, New South Wales in June 2012.
The Wallabies have been the most impressive team at the tournament so far but it will be interesting to see how they cope without David Pocock in the backrow, even if fellow turnover king Michael Hooper is returning from his ban, as he is the fulcrum of their rolling maul and without Israel Folau at full-back, who has been making massive metres without anyone really noticing.
Head coach Michael Cheika has been talking the contest up as their hardest yet but that is part of the mind games to maintain focus and not wind up the opposition with perceived arrogance. Playing England and Wales on back-to-back Saturdays should have had some physical effect and this is not a harder task. Ireland or Argentina next week will be a step up again and they will want to leave something in the tank.
Australia are the superior side but Scotland are an ever-improving unit, especially tactically, under Vern Cotter and while losing hooker Ross Ford and lock Jonny Gray to suspension puts their set-piece under pressure, stand-ins Fraser Brown and Tim Swinson are safe pairs of hands at club level that look ready to perform at the top level.
Scotland's side of the scoreboard should tick over through the boot of skipper Greig Laidlaw and fly-half Finn Russell has regularly demonstrated he can put his pack in the right place for a rolling maul powered by nationalised Kiwis Blair Cowan and John Hardie and call the right moves a backline that is now showing true potency.
The underdogs are also boosted by the availability of Ross Ford and Jonny Gray, who have been cleared to play after winning their appeals against suspensions.
And this makes a bet on 42 or more points look worthwhile too. Scotland's defence has struggled against South Africa and Samoa in the last two weeks and Australia's recycling of possession and backline running angles have been excellent so far.