Third-placed Brazil joined them in sealing Olympic qualification, with silver medallists the United States already assured of their place from last year's Eventing World Championships.

The US had led through the first two days of eventing competition, going into the jumping phase with 86.2 points, followed by Brazil with 101.5 and Canada with 105.2

However, they were denied by just one-tenth of a point, Canada's Lindsay Traisnel, Karl Slezak and Mike Winter producing fine displays to finish on 115.6 collectively at the Escuela de Equitación Regimiento Granaderos.

Errors by Sharon White and Elisabeth Halliday in the jumping phase contributed to the US having to settle for silver with 115.7, and Brazil took bronze with 127.1.

Mexico were a distant fourth with 253.0 points.

Caroline Pamukcu scored 30.8 points to take individual gold, with Márcio Jorge of Brazil earning silver with 32.2 and Traisnel bronze with 34.2.

The medals table-topping US enjoyed a more prosperous day in search of golds than the previous two, sealing a 10 kilometres open water swimming double through Brennan Gravley and Ashley Twichell at the Laguna Los Morros.

Twichell held off Brazil's defending Pan American Games and Olympic champion Ana Marcela Cunha in impressive fashion to win the women's race by 13 seconds with her time of 1 hour 57min 16.4sec, while Gravley prevailed in a thrilling finish to the men's event.

He clocked 1:50:23.4, beating Argentina's Franco Cassini by 0.2 seconds and Mexico's Paulo Strehlke by 0.4.

Gold medals in canoe slalom were split between the US and Brazil on the Aconcagua River.

Joshua Joseph in 91.12sec and Evy Leibfarth in 102.32 sealed a men's and women's kayak double for the US, and were joined on top of the podium by their compatriot Zachary Lokken, who defended his men's canoe title in 95.87.

Brazil's Ana Sátila enjoyed a double success in the women's canoe and kayak cross, and Guilherme Mapelli was the other winner in the men's kayak cross.

In the women's basketball final at the Polideportivo in the National Stadium cluster, Brazil avoided an upset against Colombia to make it back-to-back golds, triumphing 50-40.

Colombia earned a first-ever women's basketball medal at the Pan American games with their silver, and Argentina overcame Cuba 75-66 to take bronze.

The singles finals in tennis on Central Court at the Centro Deportivo de Tenis were both won in straight sets.

Laura Pigossi of Brazil dominated the women's decider against Argentina's María Carlé 6-2, 6-3, but there was a gold for Argentina through Facundo Díaz Acosta, winner of the men's final 6-3, 7-6 against Chilean home favourite Tomás Barrios Vera.

Golds on the second day of judo were shared between Brazil and Cuba.

Gabriel Falcão Lira took men's under-73 kilograms gold for Brazil by default with his compatriot Daniel Cargnin injured from the semi-final, and Guilherme Schimidt triumphed against Chile's Jorge Pérez in the men's under-81kg final.

Cuba's two golds came through Maylín del Toro Carvajal against Canada's Isabelle Harris in the women's under-63kg and Idelannis Gómez against Puerto Rico's María Pérez in the women's under-70kg.

The US continue to hold an overwhelming lead on the medals table, their tally of 68 golds nearly doubly Mexico's 35 in second.

Another successful day for Brazil helped them climb into third on 34 golds, one above Canada.