Australia will meet New Zealand in a crucial men's sevens clash on Tuesday, likely needing an upset win to remain in the medal hunt after a horror half of rugby threatened to derail their Olympic campaign just as it began.
Tim Walsh's side allowed four first-half tries in what finished as a 29-19 loss to Argentina on Monday morning, returning later in the day to notch a 42-5 win over minnows South Korea.
Wallabies centre Samu Kerevi justified his shock late call-up into the side, giving them a chance with a solo try against Argentina then laying a crucial tackle to deny South Korea what would have been the game's first try.
The top two sides from all three pools will progress to the decider, as well as the next two best third-placed teams.
Australia will finish second with a win against New Zealand, who beat Argentina on Monday, and importantly avoid them or Fiji in the early knock-out rounds.
Australia only just snuck into the Olympics, a last-minute try the difference in a tense 19-12 defeat of Samoa in the Oceania playoff.
But the Aussies were fourth in the World Series before it was halted due to COVID-19 last year and entered Tokyo with quiet confidence of challenging for a medal.
They have no room for error now and will need to improve sharply, exposed in the air by Argentina when they failed to field the first three kick-offs, starving them of ball for a majority of the opening seven minutes.
They were sloppy with ball in hand too; cheap turnovers and two kicks out on the full from restarts by livewire playmaker Maurice Longbottom summing up their day.
Elsewhere, defending champions Fiji survived two close calls against Japan and then Canada, scoring the last two tries of the game to avoid a massive boilover against the hosts.
Britain, who are in Fiji's pool, were impressive on day one, pairing 24-0 and 34-0 victories over Canada and Japan respectively.
Australian Associated Press