Racing started in the afternoon at Porto Alregre with Juan Grimaldi (ARG) going on to beat Daniel Mendoza (PER) in the first race of the day in the open division.
But Mendoza picked up his first win of the regatta shortly after inflicting Henrique Haddad's only loss so far in the third round robin.
Buoyed by his first victory, today's semi-final between Grimaldi and Mendoza could be an interesting affair.
The winner will face Haddad who is new to racing the Elliot 6m, "It's my first race with the Elliott 6m and I have found it easy and fun to sail.
"It has good speed and is very nice. Our crew is heavier than the Argentineans and the Peruvians so that has definitely favoured us so far."
In the women's division Argentina's Martina Silva is yet to win a race. She lead Peru's Tania Zimmermann in one of their two races in the day but Zimmermann overtook the Argentinean near the finish. And heading into today's semi-final the momentum is with Zimmermann.
The winner will go on to face Juliana Senfft, ranked #19 in the world, who is yet to lose a race on her home waters.