Australians Stephanie Gilmore, Tyler Wright and India Robinson have advanced to the quarter-finals of the World Surf League event in Portugal.

Stephanie Gilmore has won a tight battle with countrywoman Sally Fitzgibbons to be among three Australians advancing to the quarter-finals of the World Surf League event at Supertubos in Portugal.

Both seven-time world champion Gilmore and Fitzgibbons found a good score with big backside turns on the lefts, and Gilmore made the difference with a higher backup to win their heat 11.0 to 10.27.

"Sally is an amazing athlete and she's always on the hunt," Gilmore said

"You have to stay on top of your game and you have to want it really bad, so I was doing my best out there."

Gilmore, who next faces France's Johanne Defay, was joined in the last eight by fellow Aussies Tyler Wright and India Robinson.

Two-time world champion Wright (14.17) found a nice barrel and eliminated Gabriela Bryan (6.20) of Hawaii to set up a clash with five-time world champion Carissa Moore.

Robinson (10.34) ousted Hawaii's Malia Manuel (9.73).