In what proved an arduous fourth day of racing off the Argentine coast, sailors spent around eight hours out on the water in total as wind hovered between 10 and 12 knots on a course made difficult by the presence of weeds.

After a 10th place in the day's opening race, Lecointre and Defrance produced a brilliant performance to win the second before placing sixth in the third.

"It was hard for the nerves today, because of all the weeds," admitted Lecointre.

"There is more pressure because every time you catch one you slow down so much and it changes all your strategies as well."

The duo ended the day on 25 points after seven races, three clear of Xiaoli Wang and Lizhu Huang of China, who rose to second overall after a first and a second place finish today.

Sydney Bolger and Carly Shevitz of United States now lie in third place on 32 points, while reigning Olympic champions Jo Aleh and Polly Powrie of New Zealand rose four places up the leaderboard to fifth.

They lie on 43 points, seven behind defending world champions Lara Vadlau and Jola Ogar of Austria.

All cards remain up in the air in the men's competition on what proved a disappointing day for both leading duos.

Spain's Onan Barreiros and Juan Curbelo assumed the lead after race six after a disappointing 22nd place finish for South African co-leaders Asenathi Jim and Roger Hudson. 

But the celebrations were short lived as a 19th place in race seven unseated the Spaniards as they fell to seventh overall by the close, with Jim and Hudson ninth.

Paul Snow-Hansen and Daniel Willcox of New Zealand moved into the lead on 37 points after two victories, two clear of Croatian rivals Sime Fantela and Igor Marenic.

Australia's six-time defending champion Mathew Belcher showed ominous form with partner William Ryan with just two races to go until the medal race finale, moving to third on 48 points.

Action is set to conclude with the final race on Saturday (February 27).