RIO DE JANEIRO – Seven years may seem like a long time to some. When Rio was named an Olympic host in 2009, Carla Marqui wasn't sure it was enough, knowing how much work it would take to prepare the city for the 2016 Summer Games.

Saturday, the resident of São Paulo state walked around Barra Olympic Park with two friends, beaming at the handiwork of her country. The party that began at Friday's Opening Ceremony for the Rio Games spilled over into the first day of competition, drawing thousands of Brazilians to the main cluster of venues to take it all in. Marqui had driven seven hours to be part of it — and she planned to make another round trip later in the Games to see beach volleyball and a soccer game.

"I wasn't really sure if everything would get done in time," Marqui said, noting the Brazilian penchant for tardiness. "But it looks great, and everything seems pretty organized. It just shows you that even though we're going through hard times, we overcome them and put on a happy face. That's just how Brazilians are."

Rio Olympics organizers were counting on the start of competition to push the focus of the Games away from the city's many problems and onto the feats of the athletes. The Games got off to a mixed start Saturday, with some stirring performances, some new worries and another dose of Brazil's high spirits.

The day featured competition in 21 sports. U.S. shooter Ginny Thrasher won the first gold medal of the Rio Games, topping the podium in women's 10-meter air rifle, and British swimmer Adam Peaty set a world record of 57.55 seconds in the men's 100-meter breaststroke.

Not everything went off smoothly. There were long waits to enter some venues, and lines for water and food snaked along concourses. Choppy water at the rowing venue caused a Serbian pair to capsize, dumping them into the contaminated water at Rodrigo de Freitas Lagoon.

There also were two security scares. A small explosion went off near the finish line of the men's cycling road race at Copacabana Beach; no one was injured, and news reports said the blast was a controlled explosion of an unattended bag. At the equestrian center, which is near a military compound, a stray bullet pierced the roof of the media tent in what an Olympics official called "an unfortunate incident."

The overall mood of the day, though, reflected the essence of Brazil that permeated the Opening Ceremony: a love for life, sport and fun.

"There is so much happiness in the air, it is contagious," said Brazilian beach volleyball player Barbara Seixas de Freitas, who won her first match at the loud and lively stadium on Copacabana Beach. "It is a very intense feeling. It is very moving."

Like Friday's stripped-down Opening Ceremony, the Olympic Park clearly was built on a budget. Venues such as the Olympic Aquatics Stadium, where swimming events started Saturday, are modest and utilitarian. They sit on acres and acres of concrete, some of it painted green to simulate grass.

In a city where winter is only a concept, the park offered little shade to escape the broiling Brazilian sun. It has no green space, save for a handful of spindly palm trees and a bit of wan-looking vegetation. Saturday, people crowded under umbrellas at outdoor tables and held flags over their heads to get a break from the rays.

The sun, though, just added to the sense of place for the first Olympics in South America. The park teemed with Brazilian style, from aviator sunglasses to smart fedoras. At several sets of Olympic rings scattered around the grounds, the locals showed off that casual-cool pose Brazil has perfected. Nobody looked like a dorky tourist, not even the couple wearing matching green-and-yellow umbrella hats.

There were swaths of empty seats in some venues, including women's rugby. Chelsea Tredupp of Denver said it took two hours to get into Deodoro Stadium, a delay made less upsetting by the kindness of Rio's residents.

"It's been hectic," she said. "But the local people were so helpful. They were willing to show us how to get here, even though they were going in a completely different direction."

Some of the locals continue to protest the Games, believing they benefit only the rich and take resources away from Rio's poor. During the Opening Ceremony, demonstrators lit Brazilian flags and Rio Olympics T-shirts on fire as they marched in the streets.

Patricia Vianna of Rio came to Barra Olympic Park with three friends to see men's gymnastics Saturday. She said she had been keeping up with news of the protests, but she didn't know anyone who wasn't thrilled to have the Olympics in Rio.

Vianna expects the Games to bring lasting improvements, such as the renovation of its rundown port area into a vibrant plaza. The added security for the Olympics also has made her feel safer in a city where safety is an everyday concern.

"People who are angry with our president are very unhappy with the Games," Vianna said. "They say the money was supposed to go to hospitals and education.

"But I feel great about it. The port, that was a place where nobody ever thought of going, and now it's full of people. I think in the end, the people of Rio are going to be very happy we had the Olympics."

There did not appear to be many Americans at the Olympic Aquatics Stadium. It was about two-thirds full for the afternoon preliminaries. Pat Dwyer of Winnetka, Ill., said transportation was an issue; he hoped to use Uber to ride to the Olympic Park, but it wasn't possible.

Other than that, he had no complaints. "So far, so good," said Dwyer, father of U.S. swimmer Conor Dwyer. "We've been here for two days, and we love it. The people are wonderful."

Most of the crowd at the swim venue was Brazilian, and it showed another facet of the culture: its loud, proud love of sports. The announcer had to remind spectators to be quiet for the start of races, and they struggled to do so. When two Brazilians advanced in the men's 100 breaststroke, the arena burst into chants of "Brasil! Brasil!"

Expect to hear a lot of that over the next two weeks, in a place where people seem genetically incapable of being gloomy.

"This is a happy day in Brazil," said Eliane de Oliveiros, who was greeting people at a security checkpoint Saturday. "Really, we're always happy."

Staff writer Jim Souhan contributed to this report.