Building onshore winds meant conditions were expected to deteriorate throughout the day and an early decision was made to postpone competition.

"With that in mind, as well as a promising forecast for the remainder of the window and only nine heats left to surf, we're going to call today off and come back tomorrow for another look," WSL head of competition Jessi Miley-Dyer.

Saturday's lay day came within hours of two-time defending event champion John John Florence announcing his withdrawal from the tournament after injuring his left knee in his round of 16 heat on Thursday.

The American has also withdrawn from the following event at Rottnest Island and will fly home to Hawaii to have his injury assessed ahead of July's Olympics in Tokyo.

When competition resumes seven-time world champion Stephanie Gilmore faces a classic semi-final battle with in-form American Carissa Moore in the women's draw.

The other women's semi pits local favourite Bronte Macaulay against Brazil's Tatiana Weston-Webb.

In the men's draw, Newcastle's Ryan Callinan is the sole Australian standing in the quarter-finals.

The next call by organisers will be made on Sunday at 7.15am AWST.

Australian Associated Press