Jacob Preston scored his first try for Australia to secure a 36-22 victory over Fiji and send the Kangaroos into the World Cup semi-finals.
The match, played before 41,108 spectators in Brisbane on Sunday, featured four lead changes as Fiji challenged the defending champions.
Fiji began strongly, with fullback Bayleigh Bentley-Hape breaking in the opening set and the Bati's defence initially keeping Australia scoreless.
After errors, James Tedesco created Kotoni Staggs' try, but Tom Trbojevic's mistake handed Fiji pressure near Australia's line.
Semi Valemei scored from Kurt Donoghoe's long pass in the 17th minute, then Taane Milne put Fiji ahead from Brandon Wakeham's grubber eight minutes later.
Tedesco sparked an Australian response shortly before halftime, breaking from dummy-half before Sam Walker and Trbojevic combined to send Walker over.
Walker's conversion gave Australia a 12-10 halftime advantage.
Valemei's second try, set up by another Donoghoe cut-out pass, restored Fiji's lead three minutes after the restart.
Australia equalised through Trbojevic, then took control with Walker's penalty and Trbojevic's second try, which Walker converted from the sideline.
Trbojevic completed his hat-trick, but Valemei crossed for a third time from another Donoghoe pass; Fiji's five-eighth was named player of the match.
Australia will face the Cook Islands in Townsville before the semi-final at Allianz Stadium on November 8, while Fiji meet New Zealand on the Gold Coast on Saturday.