The pair, winners in 2013 and 2014 in Hyères, finished second in today's race to hold a slender one point lead on 14 points ahead of British Olympic silver medallists Hannah Mills and Saskia Clark.

London 2012 champions Jo Aleh and Polly Powrie of New Zealand lie third, a further point behind.

"There are a lot of good teams here," said Oliveira.

"They are very fast, very smart and have been sailing 470s for a long time so there is a lot of experience.

"We are trying to do our best and we'll have to see what happens.

"Everybody is working and trying to find the best way to get to the top and get a medal - sometimes a team can do better and then sometimes drop."

Tina Mrak and Veronika Macarol of Slovenia claimed victory on the day to move sixth overall.

Australia's Mathew Belcher and Will Ryan lead in the corresponding men's 470 event by just two points from Croatia's Sime Fantela and Igor Marenic, after the Croats finished first and the Australians second in the only race of the day.

Anton Dahlberg and Fredrik Bergstrom of Sweden finished third on the day and also lie third overall, 13 points behind the leaders.

The shock of the day came in the laser class when El Salvador's Enrique Arathoon claimed a surprise victory in the sixth race.

He sits 21st overall behind Australian leader Tom Burton, whose total of 22 points put him 13 clear of New Zealand's second placed Sam Meech.

Belgium's Evi Van Hacker heads the field in the women's laser radial class, with a haul of 14 easing her three ahead of Josefin Olsson of Sweden, while Australian duo Jake Lilley and Oliver Tweddell are each tied for the lead on 27 points in the men's finn class.

Stronger winds are anticipated as action continues tomorrow, before medal races on Sunday (May 1).