All eyes will be on Saudi Arabia on Saturday as they bid to show the world their stunning come-from-behind success over Argentina was no fluke, while Tunisia are also hoping to build on a promising opening result.
The Saudis, who were surprise 2-1 winners against Lionel Messi's Argentina in their Group C curtain-raiser, are 15/4 to spring another upset on Poland, while Tunisia are 11/10 to follow up their goalless draw with Denmark by beating Australia in Group D.
This fixture looked like being all-important in determining who finished third in Group D when the draw was made, but Tunisia may have other ideas now after their hard-fought 0-0 draw with Denmark.
The Eagles of Carthage have never made it out of the group stage in five previous World Cup attempts, but beating the Aussies would put them on four points and give them a realistic chance of reaching the knockout stages.
Tunisia's only World Cup win since their victory over Mexico in 1978 came against Panama in Russia four years ago yet they are 11/10 to get the better of Australia.
However, Jalel Kadri's men excel defensively - that clean sheet against Denmark was their eighth shutout in their last nine games - which doesn't bode well for the toothless Socceroos.
Australia, on the other hand, have plenty to prove after their 4-1 thrashing to France. Despite taking a ninth-minute lead through Craig Goodwin, the Socceroos were soundly beaten and that goal was to be their only shot on target.
Head coach Graham Arnold will be desperate to have midfielder Ajdin Hrustic, their most creative player and plying his trade in Serie A with Hellas Verona, back fit enough to start.
This showdown is unlikely to be a thriller as Tunisia's games rarely are. Nine of North Africans' last 12 competitive fixtures have featured one goal or fewer, so under 1.5 may be well worth considering at 2/1, in what promises to be a nervy affair.
But the Tunisians look the most likely winners and have more influential players than opponents Australia, who have now picked up only one point from their last seven games at the World Cup Finals.
With a close game expected, correct-score punters may want to opt for Tunisia to grind out a 1-0 victory, which is available at 6/1.
Saudi Arabia produced one of the biggest shocks in World Cup history after they came from a goal down to beat Argentina in their opening group game, but the next test for Herve Renard's team is to prove that victory was no flash in the pan.
Having stunned Lionel Messi and co, the Saudis now turn their attention to Robert Lewandowski's Poland and confidence should be flowing through camp.
Renard's men have now lost only one of their last nine internationals and are 15/4 to claim another victory over Poland, who were held to a 0-0 draw by Mexico after their talisman Lewandowski missed a second-half penalty.
There is no doubting that Poland have more proven performers, but cohesion and togetherness can count for plenty in international football, something that was evident in the Saudi's stunning success.
However, with a knockout place seemingly up for grabs, the pressure is now on the Green Falcons and that complicates matters somewhat.
Argentina racked up 15 shots and had three goals disallowed in that defeat and Poland will get their chances. Lewandowski is 6/5 to break his duck and claim his first-ever World Cup goal.
But there is also no guarantee Poland will keep Saudi Arabia at bay, especially given the Green Falcons twice found a way past Argentina and also beat the likes of Australia and Japan in qualifying.