Australia's Sally Fitzgibbons will chase an elusive world title after securing her spot in next month's inaugural World Surf League finals.

The overnight cancellation of the Tahiti Pro due to the COVID situation in the Pacific Island nation means the Corona Open in Mexico is now the final event of the regular season for the world tour.

It means Fitzgibbons has been locked in as one of the top five surfers who'll face off in a winner-takes-all battle for the world title in Lower Trestles, California, in September.

"I've worked really hard on trying to grow and evolve my game because looking at that vibe, it's super hard to make that cut," she said.

"That's just the first step and then it's just getting that opportunity to go to Lowers and really let my surfing free.

"Hopefully do that really high risk surfing because I guess the whole season's been a warm up for there."

Fitzgibbons, who has finished runner-up three times in the world championship, celebrated her passage into the finals by reaching the semi-finals at Barra de la Cruz on Thursday.

The 30-year-old made the last four by defeating America's Courtney Conlogue.

Fitzgibbons waited until halfway through the 35-minute heat to catch a wave but picked the conditions perfectly, scoring a 7.17 and an 8.00 for a two-wave score of 15.17.

Conlogue could only manage 11.77 in response, with Fitzgibbons to face American Malia Manuel in the semis.

Manuel defeated France's Johanne Defay in the day's opening quarter-final heat.

Despite her loss, Defay is also locked in for the WSL Finals as she also chases a maiden world title.

World No.1 Carissa Moore continued her dominant form, scoring a near-perfect 9.80 in her quarter-final victory over Australian tour rookie Isabella Nichols.

Seven-time world champion Stephanie Gilmore has also secured a top-five spot to reach the finals and will face Moore in the semi-finals in Mexico after defeating Tatiana Weston-Webb in the last quarter-final on Thursday.