The men's and women's 470 classes of sailing competition started in the 2016 Olympic Games here on Wednesday as Croatia and Japan took the lead respectively.

Croatia's pair of Sime Fantela and Igor Marenic topped the overall ranking after two races, while Australian Matthew Belcher and Will Ryan were second placed. Belcher was the gold medalist in the London 2012 Olympic Games.

"Tomorrow is just like the first day for us, you know it's different course, different wind. Every day is a day for itself, this (lead) means nothing," said Fantela.

In the women's 470, Japan's pair of Ai Kondo Yoshida and Miho Yoshioka took the lead. New Zealand's gold medalists from the London 2012 Olympic Games, Jo Aleh and Polly Powrie were disqualified from Race 1 but bounced back to finish Race 2 with a first place. According to the rules, the lowest round of score will be discarded, New Zealand's pair still have chances to challenge the Japanese.

In the men's laser, Tonci Stipanovic of Croatia extended his overall lead to 11 net points. Nick Thompson from Britain was second.

There emerged a new leader in the women's laser radial, with Ireland's Annalise Murphy holding off Ann-Marie Rindom from Denmark by one point. Former leader Xu Lijia from China went down to fourth place overall.

In the Finn class, Giles Scott from Britain extended his lead with a second and a first in Wednesday's two races.

"It was quite nice to get some windy conditions to grunt up, it was really full on racing today. Rio was kind to us on the outside courses. When we towed in past in the races inside the bay it looked like a completely different world. It was quiet surreal," said Scott.