Australia's Sally Fitzgibbons faces a hard path if she wants a third WSL tour win in Brazil after an opening round defeat to local veteran Silvana Lima.
Fitzgibbons, a winner in Rio de Janeiro in 2012 and 2014 as well as a two-time runner-up, faced two Brazilians in her opening round heat of the Rio Pro with Tatiana Weston-Webb the other surfer in the heat.
Despite having defeated Lima in the quarter-finals of the Bali event last month, Fitzgibbons had no answer for the 34-year-old who dropped a 13.20 two-wave score out of 20 to beat Weston Webb's 13.10 and Fitzgibbons 9.93.
It means Fitzgibbons will now face an elimination heat against fellow Australian Nikki Van Dijk and Brazil's Taina Hinckel to stay in the event.
Defending event champion Stephanie Gilmore also had a losing start on Thursday (Friday AEST) with America's Coco Ho (11.60) outpointing the seven-time world champion (10.00) and Hinckel (8.63).
Despite the defeat, world No.1-ranked Gilmore avoids an elimination heat and moves straight into round three.
In the men's competition, 2018 tour runner-up Julian Wilson continued his resurgence.
After a disappointing start to the year, Wilson made the semi-finals at Margaret River and the Australian got off to a good start in Rio scoring 12.67 to defeat Brazil's Michael Rodrigues (9.06) and American Ezekiel Lau (6.00) to move into the third round.
Newcastle's Ryan Callinan, Australia's highest ranked male surfer on tour at No.7, also made a winning start defeating fellow Australian Wade Carmichael and Brazil's Jesse Mendes to ease into the round of 32.
Carmichael is one of three Australians facing elimination in the second round along with Jack Freestone and Adrian Buchan.
The next call for the Rio Pro will be made on Friday at 6.30am (1930 AEST).