Men and women in skimpy swimsuits frolicked in the surf, sprawled out on towels or kicked around a soccer ball at Copacabana Beach. Others cooled themselves under an umbrella at one of the many open-air kiosks serving food, beer and the local sugar cane cocktail, caipirinha.

Inside the Olympic beach volleyball venue, the atmosphere was only slightly less festive.

With a DJ spinning a samba beat and thousands cheering on their hometown teams, the Olympics' sexiest sport returned to its spiritual home on Saturday for an opening session that brought out the best the beach has to offer.

Defending champion Kerri Walsh Jennings and her new partner, April Ross, easily won their opening match with a 21-14, 21-13 victory over Australia that began at 12:34 a.m. and took just 35 minutes. Fellow Americans Casey Patterson and Jake Gibb also won their opener, beating Qatar 21-16, 21-16 on a day U.S. Secretary of State John Kerry visited the venue (as did Italian Prime Minister Matteo Renzi).

Fans sang, waved their flags and cheered on their teams for the four matches on a sun-baked morning at the temporary stadium erected on this city's signature strip of sand. (Two more were to follow in the afternoon and evening.) Players kicked up sand as they dived for the ball, celebrated points with hugs and high-fives, and invariably saluted the crowd when walking off at after their matches.

"I love South American fans, and I love how the people love sports," said Argentina's Georgiana Klug, who lost her opener with Ana Gallay, falling to Spain in straight sets. "All the singing, dancing — it makes me feel like home."

Beach volleyball joined the Olympic program at Atlanta in 1996, but for most Summer Games the venue has been built in a park (or parking lot), with thousands of tons of sand trucked in to create the playing surface. For the first time since Sydney in 2000, the sport is returning to an actual beach.

And there's none more fitting. 

With the party ready to start both in and outside the arena, Italian Adrian Carambula got things started with his trademark Skyball, a high and spinning serve that wanders into the path of the sunshine and wind and confounds attempts at a return. Although he typically uses it sparingly, Carambula said he was egged on by his friends to start things off with a little flair.

"They said they wouldn't talk to me if I didn't," he said in a post-match interview that was twice interrupted because the prime minister asked him to come over and pose for a picture.

"My legs were shaking" before the first serve, said Carambula, who with Alex Ranghieri beat Clemens Doppler and Alexander Horst 21-14, 21-13. "When I walked in I actually got a little bit emotional. I wasn't expecting it, but I embraced it and I played with it. So very special."

The biggest crowd — and the most vocal support — was for Brazil's reigning world champions Alison and Bruno, who beat Canada in a straight-set but razor-thin 21-19, 22-20 victory. In the morning session's other match, Austria beat Costa Rica in straight sets.

In the afternoon, Brazil's Agatha and Barbara needed three sets to get past the Czech Republic; the Dutch men beat Russia in straight sets and the women did the same to Venezuela.

In the early part of the night session, the Spanish men beat Austria and Poland beat Germany. China held off Switzerland in a match that had to resume after a challenge on match point was reversed.