Superstar surfer Steph Gilmore has taken a big step towards this year's World Surf League finals, winning her opening heat at the Tahiti Pro.

Gilmore, currently fourth in the world rankings heading into the 10th stop on the WSL Tour at Teahupo'o, moves straight into the quarter-finals with her heat win over Costa Rica's Brisa Hennessy and fellow Australian Isabella Nichols as the event got underway on Tuesday.

The opening heat was the first time the women's tour has competed at the world famous reef break in 16 years, making it seven-time world champion Stephanie Gilmore's first heat at the venue.

Gilmore scored a two-wave total of 7.50 out of 20 in sluggish conditions to finish ahead of Hennessy (5.60) and Nichols (2.67).

The win could be crucial for Gilmore with the top five-ranked surfers in the men's and women's tours at the end of the Tahiti Pro qualifying for next month's finals in California where the world titles will be decided.

"I was so nervous and excited," Gilmore said of competing in Tahiti.

"My strategy was to just make sure that I stayed busy ... that was my plan. There wasn't many waves but it worked out."

The win over fifth-ranked Hennessy gives Gilmore an edge over her nearest rival in the race to reach finals.

"Because I had Brisa in there ... she's right there and trying to get into the top five so for both of us we were like, 'alright this is a really important heat for us'", Gilmore said.

Two-time world champion Tyler Wright is however in real danger of missing out on the top five after falling into the elimination round.

Wright, who is seventh on the rankings after effectively missing three events due to COVID-19 and visa issues, could only finish second in her heat behind France's Johanne Defay.

It means the Australian will need to come through a sudden-death heat against American Lakey Peterson to stay in the race for a spot in the finals.

Defay, as well as top-ranked Carissa Moore, are the only two women's surfers to secure their spots for the WSL finals.

Moore has also sewn up the No.1 seeding in California after she won her heat on Tuesday against America's Gabriela Bryan and France's Vahine Fierro.

On the men's side of the draw, No.1-ranked Filipe Toledo and Australian Jack Robinson have already secured their spots in the Finals.

Compatriot Ethan Ewing, who won at J-Bay last month, sits third in the rankings and so is in a good position to advance.

The next call for the event will be on Wednesday morning (Thursday AEST).