Points leader South Africa crashed out in Saturday's group stage of the season-ending World Rugby Sevens Series tournament at Los Angeles, opening the door to the crown for three rivals.
Host United States defeated the Blitzboks 21-7 in the opening match and New Zealand edged South Africa 17-14 to deny the season leaders a quarter-final berth from Pool B.
That left Australia, Argentina and Fiji still in the chase to overtake South Africa for the overall title after all three advanced to the last eight.
Sunday's quarter-final pairings include undefeated Fiji against the United States, Ireland against unbeaten New Zealand, Kenya against the unbeaten Aussies and undefeated Samoa against Argentina.
Australia took a critical 19-14 Pool A triumph over Argentina as well as blanking Japan 61-0 and ripping Spain 54-0 in the night's last match.
The South Africans, who won last month's Commonwealth Games crown and the year's first four events, could have clinched the title by reaching the final.
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Instead, Australia, which trailed 124-122 entering the weekend, has the best chance to overtake them with Argentina six back and Olympic champion Fiji on 104.
Under a special points system used this season due to Covid-19, each team's total includes its best seven results from the year.
That means Australia would take a first-ever title with a top-three finish while Fiji and Argentina must win Sunday's final and have help to capture the trophy.
Argentina must have the Aussies lose in the quarter-finals to sustain any title hopes.
The South American squad has never won the title and won its only tournament this season at Vancouver.
Four-time champion Fiji rolled through Pool C, defeating Wales 28-12, France 29-19 and Ireland 21-7.
The Samoans dominated Pool D, beating Kenya 33-14, Scotland 22-7 and England 31-5.
New Zealand downed the hosts 33-12 and Canada 26-5 in its unbeaten Pool B run.