The spirited UAE lost to Australia 0-1 in a nail-biting encounter on Tuesday at the Mohamed bin Zayed Al Nahyan Stadium in Abu Dhabi.
Veteran striker Tim Cahill scored for Australia in the 75th minute, minutes after entering the pitch, making use of a perfectly executed volley in front of the goal from Brad Smith.
Cahill has scored more spectacular goals for Australia - his stunning volley against the Netherlands at the 2014 World Cup comes to mind - but few have been more important.
Unfazed by Australia's lead, the Emiratis attacked in the hope of scoring an equaliser, but the guests used their well-organised defence to launch counter-attacks and to manage the remaining time of the match to seal a precious away win.
A last minute free-kick gave the Emirati players and 40,000 strong fans hope of leveling the match, but midfielder Omer Abdul Rahman's ball hit the wall of Australian defence, after which the referee blew the final whistle for the guests to maintain their unbeaten lead of the group.
The match saw both sides squandering several chances, the closest of which was Aaron Mooy's second half missile from outside the box that hit the Emirati wood work.
The UAE's next match will be against Thailand who lost 0-2 earlier on Tuesday to Japan.
The UAE was riding high after beating Japan in their opening match of the decisive third stage of Asian qualifying and would have fancied their chances of a second win in the 30 degrees Celsius temperatures on Tuesday.
Instead, it is Australia who return atop Group B with Saudi Arabia after two rounds as they chase one of the two tickets to Russia in 2018.
"It was an important goal, the UAE played really well, we have a lot of respect for this team," Cahill said in a sideline interview, his shirt drenched with sweat.
"But our team tired them out, we kept pressing, we kept pushing, we were patient and (it was a) disciplined performance.
"In the end, I got the reward but it's about the team. I'm so glad happy we got the points, it means so much to our country."
The 1-0 victory, which came on the back of a 2-0 win over Iraq in Perth last week, was all the more impressive for the way the Asian champions kept up the pace of the game despite the conditions.
The Socceroos next travel to Saudi Arabia on October 6 before returning to Melbourne to take on Japan five days later in a match that could go a long way to deciding whether Australia reach a fourth straight World Cup.
With Cahill having scored five of Australia's 11 goals at World Cup finals, Postecoglou will not be alone in hoping the 36-year-old's legs hold out for another couple of years.