RIO DE JANEIRO (AP) — Breezing to a three-set victory in their Olympic debut at home, the Brazilian women ran around the court perimeter slapping hands with any fans they could reach.

Captain Fabiana and her teammates only wished they could have high-fived every single supporter inside Maracanazinho arena on Saturday to show their appreciation.

"I was emotional. It's very important because all of those fans are always showing their care to us," the four-time Olympian said after dispatching Cameroon 25-14, 25-21, 25-13. "It's the least we could do and I want to compliment them for all of their support."

Karch Kiraly's top-ranked U.S. women also looked strong in their opener, topping Puerto Rico 25-17, 25-22, 25-17.

Not that the Americans thought they were even close to consistent enough. Libero Kayla Banwarth said she was "working out some first-night jitters."

"It's a good start," Kelly Murphy said. "We have some areas we can improve on in order to achieve our ultimate goal throughout this tournament. You try as much as you can to tell yourself this is a normal volleyball game, just do what we always do, but sometimes you look up and you see the Olympic rings or you see the big crowd, but I think we do a good job of just coming together and doing what we do every day."

Afterward, Murphy obliged a group of fans with selfies.

New mom of two and 2012 U.S. Olympic star Destinee Hooker watched from North Carolina, and it hurt a little bit not to be here. She said she misses being part of the Americans' close-knit roster, having given birth to her son this past spring after having a daughter post-London.

"It's not easy at all," she wrote in a text message. "Wish them the best of luck."

Earlier, the Netherlands pulled off the first upset of Day 1 by beating medal favorite and third-ranked China in five sets, 25-23, 21-25, 18-25, 25-22, 15-13.

It was Fabiana's idea to thank the fans after the two-time defending Olympic champions got off to a winning start.

Fernanda Rodrigues insists she and her teammates would be thrilled to thank everyone in the volleyball-crazed country if there was ever time. Constantly snapping selfies and signing autographs on the Olympic stage is no easy task.

Even for the team that is chasing a third gold medal right at home, having beaten the Americans in the championship the past two Olympics — and another title matchup already being forecast.

"It's so special. This is my first Olympic Games here and to see the people screaming and shouting for us is incredible," Gabriela Guimaraes said. "I can't find the words in this moment."

Cameroon's Christelle Tchoudjang Nana didn't mind being the first opponent for the host team and its huge, animated crowd.

"It's OK," she said, smiling. "It's a good moment. We played one of the best teams in the world."

Fist-pumping Netherlands coach Giovanni Guidetti found himself apologizing afterward for being hoarse.

For good reason, too.

His upstart Dutch team, back in the Olympics for the first time in 20 years, surprised just about everyone.

"I have no voice after the first match. I don't know how I can keep going in the tournament," Guidetti joked.

When the upset was in, the Dutch jumped and hugged. Netherlands outside hitter Celeste Plak lifted one staff member into the air in a celebratory embrace.

"This was really unbelievable, incredible," Plak said. "This shows that we can fight if we are down. China is a very strong volleyball country. Our last success was in 1996 in volleyball. Now it's our time to let people know we are Holland and we are back now."

Next up for the Netherlands will be another tough pool-play opponent for the Dutch: A matchup with the Americans on Monday.

American women's assistant Jamie Morrison coached a few of those Netherlands players on a club team in Turkey, so the performance wasn't a surprise to Kiraly.

"This group is truly gnarly," Kiraly said. "Our six teams, every match from here on out is going to take all we have."

The Dutch, too, know their daunting challenge is to get out of pool play.

"We want to make something extraordinary, not something ordinary," Guidetti said. "Our fighting spirit today was the key that we won."