The Brazilian was unstoppable in two-to-three foot waves on the long lefts at the pointbreak in the state of Rio de Janeiro.
Cardoso claimed a 9.7 from the judges before adding an 8.33 to score the day's highest heat total of 18.03 and secure a clash with Australia's Matt Wilkinson in the next round.
“Saquarema’s the best,” said Cardoso. “Event organizers even thought about holding off the event for the day, but the sets just kept coming in and I’m glad they didn’t decide to stop it (the round of 24).
"My first heat of the day had really full waves, but later on they had a better wall and I was able to catch two good ones. I’m stoked to have gotten the best scores so far and I hope to go even further in the event.”
Wilkinson booked his place in the round of 16, despite what he described as a "bad start to the year".
“I’ve been able to get some good points this event by getting into the round of 16 and the next events on the World Tour (Fiji and Tahiti) are places that really suit my style of surfing and hope to get some good results and not have that much pressure on me to stay in the Top 34 next year," he said.
Gabriel Medina was sent into the elimination in a surprise defeat to Jonathan Gonzalez but the Brazilian was able to emerge from his heat unscathed to set up a re-match with Gonzalez in the last 16.
“I never thought that I was going to win that heat,” said Gonzalez. “I spent the whole time in 2nd and I tried catching some smaller ones that actually opened up a wall for some good turns.
"That strategy ended up working because on my last wave I got the scores I needed. I’m stoked because it’s tough to face two surfers as good as Gabriel (Medina) and Willian (Cardoso) and beat them in Brazil.”
American Kolohe Andino continued to impress as he advanced directly into a last-16 clash with Jean da Silva thanks to a heat total score of 17.33.
"The waves have really gotten a lot smaller, but they still break pretty perfectly,” said Andino. “There were more rights breaking today (Thursday) and I’m glad to get into the round of 16.
"I hope to at least get into the quarters to get a good result and increase my ranking.”
Round of 16 match-ups:
Heat 1: Hizunome Bettero (BRA) vs Sebastien Zietz (HAW)
Heat 2: Kai Otton (AUS) vs Perth Standlick (AUS)
Heat 3: Kolohe Andino (USA) vs Jean da Silva (BRA)
Heat 4: Alex Ribeiro (BRA) vs Romain Cloitre (FRA)
Heat 5: Matt Wilkinson (AUS) vs Willian Cardoso (BRA)
Heat 6: Gabriel Medina (BRA) vs Jonathan Gonzalez (CNY)
Heat 7: Wiggolly Dantas (BRA) vs Keanu Asing (HAW)
Heat 8: Nathan Yeomans (USA) vs Filipe Toledo (BRA)