World No.1 surfer Sally Fitzgibbons will need to continue her strong record in Portugal to create breathing space atop the championship standings.
The Australian sits in pole position for her first world title, ahead of the season's third-last event, after unseating compatriot Tyler Wright by reaching this month's quarter-finals at Lower Trestles.
Fitzgibbons, 26, has arrived in Cascais to start the elite tour's European leg, holding a 300-point advantage over second-placed Courtney Conlogue of the US.
Portugal has been a happy hunting ground for three-time world title runner-up Fitzgibbons.
She had never failed to reach the quarter-finals until last year when she was knocked out in the fourth round.
"Cascais is a place where I've had a lot of success competitively over the years and I really have a great relationship with the beach breaks and the waves here," Fitzgibbons said ahead the competition window opening on Wednesday.
"I feel like, at some stage, if you want to be the world champion, you have to grab hold of the leader's jersey and not let go, so that's the plan.
"The title race this year is really exciting and inspiring to be apart of."
Third-ranked Wright, the reigning world champion, sits only 400 points behind Fitzgibbons after her fourth-round exit at Trestles.
Six-time world champion Stephanie Gilmore remains in the title race in fourth.
But the three Australians are set to face a significant challenge from Conlogue, who has won the past two years in Portugal.
"It's really great to have Sally, Tyler, Steph and I still going this far into the season," Conlogue said.
World Surf League organisers are expecting small swell for the initial days, with conditions to pick up towards the latter stage of the waiting period, ending on October 5.
The world tour will next head to France before ending in Hawaii in November-December.
