The world number 123 belied his ranking with a stand-out performance on day one of action at the ASP six-star event in clean four-to-five foot peeling lefthanders at San Juan.
Do Carmo took advantage of the excellent conditions to notch the highest heat total of the day - a 17.04 in the round of 144.
"That was a really good heat," Do Carmo said. "I'm lucky cause my first wave was a really good left and I wiped out on the first turn.
"But my board works good and I feel great. After that first one, I caught a little barrel and in the last seconds I got another better barrel like an eight-something.
"I could have had a better score because I fell right after the barrel on the cutback, but it's fine, I'm here with my girlfriend and we're enjoying the island."
Young Frenchman Maxime Huscenot posted the day's second highest score, including an 8.64, in his first appearance at the tournament.
"We have great conditions today," Huscenot said. "This resembles a lot my home island of Reunion so I really appreciate coming here and surf on my backside it's pretty rare and it's my strong side.
"After an average result in Bali I hope to rebuild confidence in this event, and I'm aiming a quarter-final here to better my ninth place result which is the best I've had so far this year."
Conditions permitting, the remaining round of 144 heats will be completed on Wednesday, when the next phase of the competition is scheduled to begin.
Round of 144 results:
Heat 1: Guillermo Satt (CHL), Vicente Romero (ESP)
Heat 2: Ian Gouveia (BRA) 14.33, Andre Silva (BRA) 11.07, Josie Graves (PRI) 7.96, Alex Kamkoff (USA) 3.80
Heat 3: Dimitri Ouvre (GLP) 14.27, Bruno Rodrigues (BRA) 9.60, Joao Kopke (PRT) 7.37, Eric Geiselman (USA) 6.20
Heat 4: Evan Thompson (USA) 11.20, Miguel Villalba (ESP) 7.64, David Echague (ESP) 7.47
Heat 5: Gony Zubizarreta (ESP) 12.50, Jatyr Berasaluce (EUK) 10.97
Heat 6: Santiago Muniz (ARG) 10.40, Leandro Usuna (ARG) 8.97, Damian Moro Ceballos (ESP) 3.94
Heat 7: Ty Watson (AUS) 10.33, Borja Agote (EUK) 9.90, Teppei Tajima (JPN) 8.77, Carlos Marques (ESP) 3.86
Heat 8: Eneko Acero (EUK), Carlo Zapata (PER)
Heat 9: Maxime Huscenot (FRA) 16.34, Nobuyuki Osawa (JPN) 15.23, Hunter Lysaught (USA) 7.67
Heat 10: David Do Carmo (BRA) 17.04, Yujiro Tsuji (JPN) 9.34, Abdel El Harim (MAR) 6.67, Luca Dioguardi (CNY) 5.53
Heat 11: Cristobal De Col (PER) 15.60, Bino Lopes (BRA) 12.56, Frederic Robin (REU) 10.70, Evandro Munoz (ESP) 8.70
Heat 12: Dillon Perillo (USA) 14.77, Paulo Moura (BRA) 9.20, Caio Ibelli (BRA) 4.10
Heat 13: Luke Davis (USA) 13.50, Tristan Guilbaud (FRA) 12.23, David Van Zyl (ZAF) 12.00
Heat 14: Patrick Beven (FRA) 15.87, Lucas Silveira (BRA) 10.83, Krystian Kymerson (BRA) 9.03, Matt Pagan (USA) 8.28
Heat 15: Alexandre Chacon (BRA) 13.83, Halley Batista (BRA) 9.20, Edouard Delpero (FRA) 8.82, Will Davey (GBR) 5.53
Heat 16: Beyrick De Vries (ZAF) 12.87, Chase Wilson (USA) 12.17, Adrien Valero (FRA) 8.43
Heat 17: Sidney Guimaraes (BRA) 14.67, Nic Von Rupp (DEU) 12.60, Ethan Egiguren (EUK) 7.67
Heat 18: Luel Felipe (BRA) 13.50, Frederico Morais (PRT) 11.14, Lenny Perdomo (CNY) 10.10, Freddie Meadows (SWE) 4.07
Heat 19: Carlos Munoz (CRI) 15.60, Mickael Picon (FRA) 10.34
Heat 20: Jose Ferreira (PRT) 11.17, Adrien Toyon (FRA) 7.66
Remaining Round of 144 match-ups:
Heat 21: Simao Romao (BRA), Steven Pierson (PYF), Rudy Marechal (FRA), Manuel Lezcano Cruz (CNY)
Heat 22: Davey Cathels (AUS), Miguel Tudela (PER), Romain Laulhe (FRA), Julian Del Pozo (CNY)
Heat 23: Gavin Gillette (HAW), Manuel Selman (CHL), Alexander El Naib (DEU), Natxo Gonzalez (EUK)
Heat 24: Chris Friend (AUS), Filipe Jervis (PRT), Norman Landa (EUK)