Stephanie Gilmore has concocted a pair of high-scoring waves to rescue her Bells Beach campaign and oust long-time rival Lakey Peterson.
The reigning world champion trailed for most of their round-of-16 heat on Monday but stole a wave under priority and then doubled down with another nice combination.
Her 5.63 and 5.57-point efforts (11.20 total) were just enough to pip Peterson's six and five-point waves (11).
Gilmore then allowed the American onto a wave in the final three seconds, but she was unable to produce the score she needed.
Peterson also fell on an earlier wave that had the potential to deliver her a winning score.
"I saw her smash it on the inside and thought, 'Oh no, I should have taken it'," Gilmore said of her late decision.
"But it wasn't a great wave ... things went my way; so happy to make it through."
Gilmore has never lost before the quarter-final stage at the Victorian break and, ranked 14th, needs a big result to boost herself into the top-10 and above the mid-season cut line.
"That was a crazy, important heat," Gilmore said, adding she has to "keep it rolling" after her win over 13th-ranked Peterson.
"I've got a long way to go before I can feel somewhat comfortable about the cut."
She will surf against Tatiana Weston-Webb in the final eight, the Brazilian doing what Peterson couldn't and finding a late wave to snatch a heat win.
Australia's No.1-ranked Molly Picklum also progressed, along with Isabella Nichols and defending champion Tyler Wright.
Sally Fitzgibbons was beaten by Hawaii's Bettylou Sakura Johnson, while Picklum edged another Australian, Sophie McCulloch.
Matt McGillivray beat No.2 Joao Chianca in the only men's round-of-16 heat to be contested before officials paused competition until at least 4pm on Monday.
Local wildcard Xavier Huxtable emerged as a giant killer on Sunday, shocking Australia's world No.1 Jack Robinson.
He will face countryman Connor O'Leary in the round of 16.
Jackson Baker and Ryan Callinan will also fly the flag, but the USA's multiple world champion Kelly Slater's elimination left him in grave danger of missing the mid-season cut.
