Olympic champion Xu Lijia led the overall ranking after two rounds in the women's laser radial when the 2016 Olympic sailing competition begins on Monday.
After she won in London, Xu retired. And Only nine months ago, she resumed training and participated in her third consecutive Olympics.
Xu ranked third and fourth in the first two rounds respectively, putting her to lead the overall ranking.
"I felt OK in the races," said Xu. "I enjoy sailing more and more."
"I'm so happy to be back on the boat again because I had some injuries and couldn't train properly. It really feels a very precious time. I want to embrace every second of it."
"I injured my shoulders two months ago and couldn't do upper body training but I did keep lots of endurance and lower body training, like cycling. Today I got the opportunity to sail freely. My arms are a bit sore but nothing matters." she added. "I feel very focused and relaxed and I feel very familiar about the course."
Brazil's Robert Scheidt began his sixth Olympic Games on home soil. The Brazilian legend returns to the laser class in which he won his first Olympic medal (gold at the Atlanta 1996 Games), having won silver at the London 2012 Olympic Games in the now-discontinued star (keelboat) class.
Scheidt became seventh overall after two races on Monday.
"Of course it's always better to start well than not. The guys who got two top tens are confident, but having said that there are still a lot of races to go. It's too early in the regatta to talk about points."he said.
Croatia's Tonci Stipanovic led the overall ranking in the men's radial.
While in the men's RS:X, defending champion Dorian Van Rijsselberghe from the Netherlands was second overall, behind London 2012 silver medallist Nick Dempsey from Britain. In the women's RS:X, Olympic champion Marina Alabau Neira from Spain was placed fifth overall.