Australia's Sally Fitzgibbons has moved into top spot on the women's surfing world tour rankings after reigning world champion Carissa Moore bowed out early in California.
Fitzgibbons was only 200 points shy of Moore heading into the Swatch Women's Pro at Trestles, the seventh of 10 stops on the tour.
But Hawaii's Moore was beaten in the fourth round by American Lakey Peterson, assuring the Australian of the No.1 standing.
"Carissa Moore is Carissa Moore," Peterson said of defeating the two-time world champion.
"You have to surf the best you can to beat her."
Fitzgibbons will next face Bianca Buitendag in the quarter-finals after the South African disposed of Australian rookie Dimity Stoyle.
Five-time world champion Stephanie Gilmore, Laura Enever and Tyler Wright also enjoyed wins to progress to the last eight.
The men's competition wasn't without its own shock losses, with world No.1 Gabriel Medina and veteran Kelly Slater both going down in their opening round heats of the Hurley Pro.
Carlos Munoz, the first Costa Rican to compete in a world championship tour event, fed off crowd support to upset Brazilian superstar and last round's winner in Tahiti, Medina.
"I can't believe it. When I heard the score, I started crying," Munoz said.
American Tanner Gudauskas said luck played a part in his toppling six-time Lower Trestles victor Slater, who - together with Medina and Australian veteran Taj Burrow - face elimination in round two.
Australians Adrian Buchan, Mick Fanning, Joel Parkinson and Owen Wright all won their opening heats for direct entry into the third round.
