The Brazilian came through his heat with a near-perfect display of surfing, claiming the day's highest combined total of 19.27 in clean two-to-four foot waves.
"That was a fun heat and a good way to start for the rest of the comp," Medina said. "In the beginning of the heat I was catching too many lefts and I thought, ‘maybe I can get a right.’ I got that one and got the 9, so it was a good heat."
Local favourite Tanner Gudauskas of San Clemente notched a single-wave score of 9.27 on his way to a combined total of 16.77.
"I’m stoked because at that point the heat was going so fast, there were a lot of waves and I didn’t have to think about it,” Gudauskas said. “I just like surfing Lowers and that always adds to the psych. It was good to get the ball rolling and I’m just having fun watching everyone surf.”
Hawaii's John John Florence was also on good form as the latest stop on the ASP World Tour got under way.
But Australian Julian Wilson bowed out of the competition, despite posting one of the best single-wave scores of the day after a huge frontside air-reverse.
"My last three events here, I’ve lost because of interference,” Wilson said. “It’s frustrating because the waves are so good. I’m not 100 percent now, but that’s no excuse. It’s hard, it’s my sponsor’s event and you always want to do well for them.”
Heat 1: Tomas Hermes (BRA) 13.76, Jeremy Flores (FRA) 13.56, Aritz Aranburu (EUK) 12.97, Caio Ibelli (BRA) 11.83
Heat 2: Fredrick Patacchia (HAW) 13.16, Sebastien Zietz (HAW) 10.50, Jay Quinn (NZL) 10.40, Davey Cathels (AUS) 10.20
Heat 3: Evan Geiselman (USA) 13.60, Tim Reyes (USA) 12.84, Kolohe Andino (USA) 12.57, Brent Dorrington (AUS) 7.93
Heat 4: Gony Zubizaretta (ESP) 14.60, Billy Stairmand (NZL) 13.94, Royden Bryson (ZAF) 13.54, Nic Von Rupp (DEU) 12.97
Heat 5: Glen Hall (IRL) 14.30, Kai Barger (HAW) 13.94, Miguel Pupo (BRA) 13.87, Garrett Parkes (AUS) 12.40
Heat 6: Travis Logie (ZAF) 15.73, Kekoa Bacalso (HAW) 12.63, Hizunome Bettero (BRA) 12.20, Alex Ribeiro (BRA) 9.57
Heat 7: Taylor Knox (USA) 15.17, Nat Young (USA) 12.04, Vincent Duvignac (FRA) 10.67, Brandon Jackson (ZAF) 7.20
Heat 8: John John Florence (HAW) 16.53, Marc Lacomare (FRA) 14.03, Joan Duru (FRA) 11.40, Dean Morrison (AUS) 11.00
Heat 9: C.J. Hobgood (USA) 16.03, Cory Lopez (USA) 14.37, Jeronimo Vargas (BRA) 12.46, Stu Kennedy (AUS) 10.37
Heat 10: Gabe Kling (USA) 14.03, Raoni MOnteiro (BRA) 13.63, Tonino Benson (HAW) 12.67, Hodei Collazo (EUK) 9.60
Heat 11: Tanner Gudauskas (USA) 16.77, Adrien Toyon (REU) 15.43, Joel Centeio (HAW) 14.43, Olamana Eleogram (HAW) 12.34
Heat 12: Mitchel Coleborn (AUS) 16.10, Jeffrey Lukasik (USA) 14.76, Julian Wilson (AUS) 14.45, Lincoln Taylor (AUS) 13.94
Heat 13: Gabriel Medina (BRA) 19.27, Heath Joske (AUS) 14.27, Chris Ward (USA) 12.76, Ricardo Dos Santos (BRA) 9.00
Heat 14: Charles Martin (GLP) 14.43, Jesse Mendes (BRA) 13.10, Dion Atkinson (AUS) 12.93, Maxime Huscenot (FRA) 10.84