Eight-time world surfing champion Stephanie Gilmore remains winless in her return to full-time competition, suffering a narrow round-one loss at Margaret River.
Canadian Erin Brooks, the women's rookie of the year last season, beat the Australian 12.50 to 12.24 on Thursday as Main Break produced pumping conditions.
Gilmore needed a 6.67 wave score after she and Brooks ended their tight heat with solid rides, but the judges denied the surfing great with a 6.37.
Jake "Snake" Patterson, who coaches the two surfers, thought Gilmore had done enough with her last wave to win the heat.
"That for me was the best wave of the heat," Patterson told a downcast Gilmore.
Brooks' gamble paid off as she went left, instead of right, and picked up a 6.00 score late in the heat that gave her the lead.
"That definitely was not how I wanted that heat to go," Brooks said.
"I got behind so much, so I went on that left because no one was looking and luckily I got through."
Gilmore, a wildcard entry this season after her World Surf League sabbatical, also lost in round one in the opening event this month at Bells Beach.
WSL organisers had overlapping heats throughout day one at the WA event to make full use of the six- to eight-foot swell.
That means they went through a whopping 28 heats, ticking off the women's first round and all the second round for the men.
As Gilmore started her heat, nearby American five-time world champion Carissa Moore was beating Alyssa Spencer.
Moore, like Gilmore, is back on the tour this season as a wildcard entry.
Australian Sophie McCulloch ended round one with a tight heat win over compatriot Bronte McCaulay. McCulloch was a replacement for Australia's two-time world champion Tyler Wright, a late withdrawal because of injury.
Sally Fitzgibbons was the other local in round one and she progressed.
In the men's first round, Jacob Willcox beat fellow local Oscar Berry. The other All-Australian heat was a win for Liam O'Brien over Callum Robson, while Jack Thomas beat Brazilian Mateus Herdy.
In round two, O'Brien had a big win over South African Jordy Smith, the defending event champion. Australian Joel Vaughan also beat Hawaiian Barron Mamiya.
Brazil's reigning world champion Yago Dora beat Willcox and Dora's compatriot Miguel Pupo, who won Bells Beach, dispatched Australian Morgan Cibilic. Thomas was knocked out by American Griffin Colapinto.
But George Pittar claimed a big Brazilian scalp, beating Filipe Toledo, as fellow Australians Jack Robinson and Ethan Ewing also advanced.
