RIO DE JANEIRO - Unflappable American teenager Virginia Thrasher won the first gold medal of the Rio 2016 Olympic Games on Saturday, holding her nerve against two Chinese Olympic champions to clinch the women's 10m air rifle event.

The 19-year-old U.S. college champion edged out China's Du Li, gold in Athens in 2004, with an Olympic-record score of 208 in the sport's new finals format. Defending Olympic champion Yi Siling, also of China, took the bronze medal.

Competing in her first Olympics, Thrasher, as the first champion of the 2016 Games, was awarded her medal by International Olympic Committee (IOC) president Thomas Bach and said the achievement was beyond her wildest dreams. The youngest of the eight finalists by several years, Thrasher established an early lead after battling with the Russian shooter Daria Vdovina, who stumbled midway through the competition and finished fifth. "About halfway through when I took the lead it kind of became clear to me that I was in contention for a medal, but I quickly pushed that thought away and focused on breathing and taking one shot at a time," Thrasher said.

Thrasher learned to love shooting while hunting deer with her grandfather when she was in eighth grade. "I got my first deer and I liked the adrenaline of pulling the trigger," she said. She then joined her high school air rifle team and was recruited by West Virginia University, where she became a national collegiate champion as a freshman this year.

With her non-nonsense style, Thrasher seemed unfazed by her seasoned field and consistently scored in the 10 points target area over the 20 rounds. Afterwards, she noted that she had not attended the Olympics' opening ceremony Friday night and had instead gone to bed early for her Olympic debut.

Like all American shooters, Thrasher faced the inevitable question of what she thinks about gun control in the United States, a hot-button issue in this election year. She responded matter of factly that the controversy over guns in America "really is just distracting from our sport, which is very different."

Easy win for first boxing pro in Games history

Italy's Carmine Tommasone on Saturday became the first professional in history to step in to an Olympic boxing ring -- and celebrated by teaching his opponent a harsh lesson in Rio.

Tommasone, 32, who came into the lightweight bout with a perfect 15-0 record, simply had too much speed, power and guile for Mexico's Lindolfo Delgado and was deservedly awarded a unanimous points decision by the judges at ringside.

The Italian hurt the taller Mexican, 21, in round two with a clumping overhand right that had Delgado smiling and urging the Italian to bring it on -- begrudging recognition that the punch hurt. He continued to bamboozle Delgado in the third and final round, hitting the Mexican around with combinations that Delgado had no reply to. "I am very proud," Tommasone said of being the first boxing pro at an Olympics.

"I was asked by my federation to come to the Olympics and I was very happy to do so -- for me, it's the most important competition in the world." The decision to include professionals at the Olympics only came in June and was met with a chorus of disapproval. Only three professionals including Tommasone made it to Rio.

Youngest US Olympian suffers opening round defeat

The United States' youngest Olympian Kanak Jha was knocked out of the men's table tennis on the opening day, after losing his singles clash with Iran's Nima Alamian on Saturday.

The quick-footed 16-year-old, the first member of the United States' Olympic team to be born in the 2000s, put up a fight against his world number 111-ranked opponent in the last three games but eventually succumbed 4-1 in the preliminary round.

"The last three games were all very close games, I had chances in all of them, (but)...especially when it's close like 9-9, 10-10, I'm a little more nervous, and then he was attacking more in those moments," he told reporters.

Jha has become a poster boy of a new generation of table tennis players in the United States, which has struggled to develop competitive talent in the sport. Massimo Costantini, the U.S. table tennis team's coach, said Jha had become nervous after his match was delayed, and his lack of experience had caused him to make some "naive choices" and mistakes that cost him the game.

"We are confident that being 16 years old and having played his first Olympics, he will build hopes for the future," he said of Jha, who currently ranks 275. Jha will still compete in the men's team event which begins on Aug. 13.

Crowds in the half-filled table tennis venue waved Brazilian flags, with the loudest cheers saved for Latin American competitors and the home team. In the women's singles category, Melissa Tapper, who is first Australian to compete in the Olympics and Paralympics, was knocked out in the preliminary round after losing 4-2 to Brazil's Caroline Kumahara.

Brazil hopes dashed for early first Rio gold

Brazilians will have to wait a bit longer for their country to earn its first gold medal at their home Olympics after reigning judo champion Sarah Menezes suffered a shock defeat in the quarter-finals on Saturday.

Menezes, who won gold in London four years ago, was considered a favourite to win the women's -48kg category before a raucous crowd at the Carioca Arena 2 who chanted "Ole, ole, ole, Sarah, Sarah" and waved the Brazilian flag.

But Menezes, the world No. 4 in her weight class, struggled to gain traction against 17th-ranked Dayaris Mestre Alvarez of Cuba and lost on a single penalty in an otherwise scoreless match. Brazil is placing high hopes on its judo team to boost its medal haul in Rio after it took home four medals in the sport at the London Games. The hosts, along with powerhouses France and Japan, are the only countries fielding a full team of 14 judokas.

Menezes and fellow Brazilian Felipe Kitadai still have the chance to reach the podium with a bronze medal later in the day through the repechage rounds.