Australia were a long way off their best but managed to overcome Georgia 27-8 in difficult conditions in Fukuroi to book a likely World Cup quarter-final against England.
Typhoon Hagibis approaching Japan led to heavy wind and rain battering the Shizuoka Stadium Ecopa, where Australia went ahead courtesy of Nic White's 22nd-minute try.
It was not until after the hour mark that they crossed the whitewash again through Marika Koroibete while Jack Dempsey and Will Genia tries gave Australia a bonus-point win after Alexander Todua had touched down for Georgia.
Australia therefore moved to the top of Pool D but they will be relegated to runners-up if Wales avoid defeat to Uruguay on Sunday, which would see the Wallabies taking on Pool C winners England in Oita next Saturday.
If that is indeed how events unfold then England head coach Eddie Jones would have taken heart from Australia's laboured display.
They lost Kurtley Beale inside the first quarter of an hour, with the full-back not returning to the field following a head injury assessment.
Michael Cheika's men routinely made errors at critical junctures in Georgia's 22 before the pressure eventually told, White burrowing over from close range midway through the half.
Australia have been criticised for their indiscipline in this tournament and it surfaced once again here, Tolu Latu's high tackle awarding Georgia a penalty, with Soso Matiashvili splitting the posts.
Number eight Isi Naisarani was yellow carded five minutes before the interval after appearing to make contact with the face of Giorgi Nemsadze with a leading arm in a ruck clear out.
Despite being down to 14 men following their fourth sin-binning of the tournament, Matt Toomua slotted home a penalty to give Australia a 10-3 lead at the interval.
Koroibete's stunning solo effort as the match entered the final quarter, in which the wing burst forward from halfway and skipped past a couple of Georgia defenders, gave Australia some breathing room.
But back came Georgia through Todua, who touched down on the left wing after being teed up by Lasha Khmaladze in the 70th minute.
However, tries inside the final five minutes from Dempsey and Genia made certain of an Australia victory.
Australia v Georgia - Match Stats
Australia: (10) 27
Try: White (23'), Koroibete (60'), Dempsey (75'), Genia (79')
Conversion: Toomua (24', 61')
Penalty: Toomua (37')
Georgia: (3) 8
Try: Todua (70')
Penalty: Matiashvili (28')
Man of the match: Izack Rodda (Australia)