China finished the first full competition day of the Rio Olympic Games without a gold medal while Vietnam made history by taking its first ever Olympic gold in shooting on Saturday.[Special coverage]
With former Olympic champion Du Li and Yi Siling on the same court at women's 10m air rifle final, US shooter Virginia Thrasher staged a steady performance to bring the first gold medal of Rio Olympics to Team USA.
Thrasher, 19, finished the match with 208.0 points, one point more than 2004 Athens Games champion Du from China. Defending champion Yi took home the bronze with 185.4 points.
"It's just an intensive feeling of pride for my country and I'm so happy to be here," said Thrasher, whose gold is also her first international competition medal.
"I was just trying to shoot the best I could for my first Olympics experience coming without any medal. The first gold medal for Rio 2016, for USA at 19 years old is incredible."
It was the fourth Olympics for 34-year-old veteran Du, who won the title at the same event 12 years ago in Athens, Greece.
"It's really hard," said the silver medalist. "There were some expectations, but It's just too hard."
The 41-year-old Hoang Xuan Vinh won Vietnam's first Olympic gold medal with his last shot in the men's 10m air pistol event.
"I'm happy that I can get the first Olympic gold for Vietnam," said Hoang after the final. "It will be my life-time memory."
Vietnam has won two Olympic silvers prior to the 2016 Games, one from weightlifting and the other from taekwondo.
Hoang beat Sao Paulo-born Felipe Almeida Wu of Brazil to second place while China's Pang Wei, Du's husband, took bronze.
Hoang said: "The Brazilian shooter is very fast and strong, but I think only 'try, try, try'. On the last shot I didn't think gold or silver. I think only try."
In swimming, Mack Horton clinched Australia's first gold medal of the Rio Olympics by upsetting favorite China's defending champion Sun Yang in the men's 400m freestyle final.
Horton clocked 3 minutes 41.55 seconds, eclipsing Sun by just 13 hundredths of a second at the Olympic Aquatics stadium. Gabriele Detti of Italy was third in 3:43.49.
Mack, who finished second fastest in qualifying, is competing at his first Olympic Games in Rio. The 20-year-old was the bronze medalist in the 800m freestyle at last year's world championships in Kazan.
Sun was the pre-race favorite, having won gold in the same event at the London 2012 Games. The 24-year-old is also the defending 1500m Olympic champion.
Hungary's Katinka Hosszu set a new world record to win the women's 400 meters individual medley. The 27-year-old finished in four minutes 26.36 seconds to beat the previous mark of 4:28.43 set by China's Ye Shiwen at the London 2012 Games.
Maya Dirado of the United States was second in 4:31.15 and Spain's Mireia Belmonte third in 4:32.39.
It was Hosszu's first podium finish at the Games, despite having netted nine world championship medals - five of them gold. Hosszu is making her fourth appearance at an Olympic Games in Rio.
Australia took the second gold in the pool as they won women's 4x100m freestyle relay in new world record.
Kosuke Hagino won Japan's first gold medal by beating American Chase Kalisz and countryman Daiya Seto in the men's 400m individual medley.
Earlier in the day, Britain's Adam Peaty broke his own world record for the men's 100m breaststroke in the heats.
In judo, Paula Pareto from Argentina and Beslan Mudranov from Russia took the women's 48kg and men's 60kg titles apiece.
The men's cycling road gold went to Belgium cyclist Van Avermaet Greg while Emese Szasz earned Hungary its first gold medal in Rio with victory in the women's epee individual event.
South Korean archers once again showed their overwhelming dominance as they outclassed a consistent American team 6-0 in the final.
Elsewhere, Sopita Tanasan of Thailand won the gold medal of the women's 48kg contention with a total of 200kg.
