In a tournament where many teams have recently made coaching changes and are going through a period of transition, Oman are surprisingly settled.
Paul Le Guen, a target for the Socceroos head coach position after the 2010 World Cup, has had three years to mould this side in his image. He has primarily focused on defensive structure with Oman, drilling them meticulously on their roles without the ball and creating a disciplined, structured unit.
At the Gulf Cup, Oman defended in three straight lines - a front two who worked hard and dropped deep to make the side compact, the wingers tracking back to form a bank of four in the midfield, and the back four behind them. Oman never pressed particularly high up, but they slid laterally across the pitch to block forward passes. Their defensive strength is illustrated by the fact they conceded just once in qualifying for the Asian Cup.
Against South Korea in the opening game, however, Le Guen made a surprising alteration to the usual 4-4-2 system. He went to a 5-4-1, essentially sacrificing a striker for extra cover at the back. This was, presumably, a system that had been worked on in the pre-tournament training camp, and for the majority of the first half against Korea, Oman actually defended quite comfortably. South Korea had lots of possession - finishing with 67 per cent of the ball - but for long periods, they lacked penetration, and were unable to work it past Oman's lines.
When Oman won the ball, they attacked quickly and directly, often through left-winger Qasim Saeed. Three times inside 20 minutes Saeed drove forward purposefully down the left, looking to combine with striker Al Muqbali, and he perhaps should have had a penalty when attacking inside the penalty box. Like Korea, Australia push their full-backs high up, so Ivan Franjic must be wary of not leaving too much space in behind.
On the opposite side, the primary threat came from right wing-back Raed Ibrahim, who got forward purposefully, and found space when cutting back inside and hitting little chipped crosses over the top for Al Muqbali. He also has a good shot, coming close to an equaliser against Korea with a fizzing low shot from range.
An area of weakness for Oman was in midfield, where the two central midfielders, Eid Al-Farsi and Ahmed Mubarak, were sometimes overloaded when Korea brought their wingers infield, between the lines. Both Lee Chung-yong and Son Heung-min found pockets of space behind Oman's midfield duo, and although they had the cover of three centre-backs behind them, it was still an area of concern - and against quick, mobile attackers like Mathew Leckie and Robbie Kruse, Australia could find joy in this zone.
It will be vitally important that Australia has creativity in central positions, because if they continually look to cross from wide positions into Cahill, Oman will have three central defenders up against Tim Cahill that are capable of winning aerial battles.
Against teams that defend in organised numbers behind the ball, it's crucial that there is variety and a high tempo in attack, in order to draw players out of position, and create gaps to play forward into. Regardless of whether Oman continue with the 5-4-1, or revert to their usual 4-4-2, their emphasis will be the same - frustrate Australia, and then counter-attack quickly.
In that sense, the challenge is very similar to the one Australia faced against Kuwait. Oman have stronger individuals and genuine quality in attacking positions, however, and so this will be a bigger test for Ange Postecoglou's side.