Sally Fitzgibbons' hopes of competing in the Paris Olympics have been dashed with the Australian team missing out on an additional quota spot for this year's Games.

The 33-year-old has a fourth title in sight at the International Surfing Association World Surfing Games in Puerto Rico, but she needed the Australian women's team to fire with the top line-up securing a third Olympic spot.

Despite boasting current world No.1 Molly Picklum and two-time world champion Tyler Wright, who have already qualified for Paris via last year's World Surf League rankings, they fell short.

Picklum and Fitzgibbons were part of a four-strong heat in the fourth round, which was won by Portugal's Yolanda Sequeira.

Fitzgibbons placed second to be among eight surfers to advance to the fifth round while Picklum was a distant fourth and then eliminated in a repechage heat along with Wright.

Fitzgibbons, who returned to the Championship Tour this year, has won the ISA event three times (2008, 2018, 2021) and finished third in 2022.

Spain currently top the women's team standings with Australia back in seventh.

There were an additional eight quota spots available to countries who hadn't already qualified two female surfers, with 14-year-old Yang Siqi becoming the first surfer from China and the youngest person to qualify for the sport at the Olympics.

The schoolgirl beat three surfers including British surf-skate phenomenon Sky Brown in Friday's heat in tricky waves at the contest site of Arecibo.

The result means 15-year-old Brown has fallen short in her efforts to represent Britain in both surfing and skating in Paris.

In the men's event only Ethan Ewing remains in contention with Jack Robinson and Morgan Cibilic bowing out, leaving the Australian men's team in fourth spot behind Brazil.

Ewing finished second in his round-five heat behind Brazilian Gabriel Medina to advance to the sixth round.

Surfers can contest up to 11 heats if they go through repechage all the way to the final, making it a marathon competition over a week.