Rual and Amoros started the day with a pair of seconds before slipping to 16th in the third race.

With every team discarding its worst finish, Rual and Amoros have a one-point advantage in the overall standings over Dylan Fletcher-Scott and Stuart Bithell of Great Britain and two points over Americans Fred Strammer and Trevor Burd and the Lange brothers, Yago and Klaus, of Argentina.

"We sailed the 29er before for one year in 2013, and we started sailing 49er together in September,” said Amoros.

"That's why we are surprised.

"We work really hard and we're happy to be here.

"But it wasn't our goal [to be in the lead at the end of day one].

"If we stay here it will be nice.”

Olympic laser and star medallist Robert Scheidt of Brazil endured a difficult debut as a 49er sailor.

Scheidt is partnering compatriot Gabriel Borges at Miami’s Regatta Park, with the high performance skiff presenting the 43-year-old with a different challenge to what he has experienced before.

He is familiar though to sailing in two-person fleets, having won Olympic silver and bronze medals in the star.

His first day of competition in the 49er class left the pair in 22nd place.

Thomas Goyard of France and The Netherlands' Kiran Badloe are tied for first in the men's RS:X class with three points.

Goyard will wear the leaders jersey tomorrow by virtue of his win in the third and final race.

There's also a tie at the top of the women's RS:X with Hei Man H V Chan of Hong Kong and Great Britain's Emma Wilson both on four points while China's Yunxui Lu is third, with seven points.

Karl-Martin Rammo of Estonia had a strong start to his Laser regatta as he earned a first and a fourth place finish in his two races leaving him five points clear of Britain's Nick Thompson with Argentine Tomas Pellejero in third with 16 points.

Evi Van Acker of Belgium, a London 2012 bronze medallist, is currently second in the radial class, three points back of Greece's Vasileia Karachaliou who has six points.

France's Mathilde de Kerangat currently completes the top three on 10 points.

Turkey's Alican Kaynar put together a first and a second to open his regatta in the Finn class and as a result leads by two points over the regatta's defending champion, Brazil's Jorge Zarif.

Great Britain's Ben Cornish is third, also with five points.

The gold medallists from Rio 2016, Martine Grael and Kahena Kunze of Brazil picked up where they left off and are leading the 49erFX class courtesy of a tie break with two other teams.

Fellow South Americans Victoria Travascio and Maria Branz of Argentina are second while the Canadian duo of Erin Rafuse and Dannie Boyd are third.

Kazuto Doi and Naoya Kimura of Japan collected a first and a fourth place finish today and have opened up a three point lead in the men's 470 class over Italians Giacomo Ferrari and Guilio Calabrò.

The Greek duo of Panagiotis Mantis and Pavlos Kagialis are third.

Afrodite Zegers and Anneloes Van Veen of The Netherlands have the early lead in the women's 470 class with four points from two races.

Sophie Weguelin and Eilidh McIntyre of Great Britain are second with six points while Spaniards Silvia Mas Depares and Paula Barcelo Martin are third with seven points.

Lorenzo Bressani and Caterina Marianna Banti of Italy have the lead in the Nacra 17 division after winning two races and discarding a second.

Tom Phipps and Nicola Boniface of Great Britain are second with four points while another British pairing, John Gimson and Anna Burnet, are third on seven points courtesy of a tie-break with Lin Ea Cenholt and Christian Peter Lübeck of Denmark.

Racing will continue from Regatta Park tomorrow at 11am local time beginning with the Nacra 17 and 49erFX divisions.