The Australian Olympians both bowed out on Tuesday, with Fitzgibbons eliminated by Brazilian Tatiana Weston-Webb while seven-time world champion Gilmore fell to American Courtney Conlogue.

Another Australian, Keely Andrew, was taken out in the last eight by Hawaiian rankings leader Carissa Moore, who won the Newcastle Cup earlier this month.

Reigning world champion Moore will face Weston-Webbin the first semi-final while Conlogue will battle countrywomen Caroline Marks, who overcame France's Joanne Defay, for a spot in the decider.

Weston-Webb made an early statement with an opening score of 6.67 in the glassy conditions in Sydney's northern beaches, which left Fitzgibbons chasing a big score.

She came up with a 6.40 for a two-wave score of 10.40 but it was short of the Brazilian's 11.90.

Gilmore struggled to get into her heat and pulled out her best score of 5.17 in the final minutes, however, it wasn't enough to catch Conlogue, who cruised into the final four.

Australian Associated Press