Nacra sailors Jason Saunders and Gemma Jones are the early pacesetters in the Rio sailing test event for the new Nacra 17 class.
The pair had two second placings in the first two races to sit top of their event.
However the day didn't go entirely to plan with Saunders taking an unscheduled dunk in their third race, when they finished 15th.
''We had a little problem after the start and I fell off the trapeze and into the water, so we were a bit behind from there and it was pretty hard to catch up," Saunders said.
"We sailed really well in the first two races, we had two great starts and sailed the shifts well. It was tough out there with the sea breeze but we managed to sail the conditions really well."
The women's 49erFX pair Alex Maloney and Molly Meech sit second overall, after a third placing then a win in the second race. They finished 15th in race three after an ordinary start, but still look in good shape as that placing will likely be a discard.
"It was a great way to start the day and leading into the third race we had some confidence going into it but just didn't quite execute our game plan," Meech said. "That win in race two was actually a bit unexpected. We were in third or fourth going round the mark in the last downwind and we played a few shifts right and we managed to take it at the end which was nice."
World No 1 crew Peter Burling and Blair Tuke are third overall, after a second in the first race and sixth in their second of the 49er class, while Olympic champions Jo Aleh and Polly Powrie are seventh overall after a fourth and 12th in their first two races.
Paul Snow-Hansen and Daniel Willcox are 14th overall in the men's 470, while Josh Junior is sitting eighth in the Finn, after seventh and 10th placings.
Laser sailor Andy Maloney was ninth and 22nd in today's two races to be eighth overall.