PHOTOS: Gold winners on Day 8 of the Games

Li Xuerui won gold in the women's badminton singles at the London Olympics after beating World champion Wang Yihan 21-15, 21-23, 21-17 in an all-Chinese final.

Wang saved two match-points in the second game but Li secured victory on her third in the decider. She then tossed her racket and raised her arms to salute the crowd in Wembley Arena.

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Li was a last-minute entry by China, which chose her ahead of former No. 1 Wang Shixian because of a 30-match winning streak this year, which included three wins over Wang Yihan.

Earlier, Saina Nehwal became only the second woman from India to medal in the Olympics when Wang Xin of China retired injured during their bronze playoff.

Serena Williams became only the second woman to complete a career Golden Slam when she won her first Olympic singles gold medal by beating Maria Sharapova 6-0, 6-1.

The victory completed a remarkable run of domination by the No. 4-seeded Williams, who lost only 17 games in her six matches. She went 13-0 this summer at the All England Club, where she won her fifth Wimbledon title a month ago.

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The career Golden Slam was first achieved by Steffi Graf, who did it when she won the Olympics in 1988 after sweeping all four major titles.

And she's not done in London. Williams and her sister Venus, pursuing their third gold in doubles, are scheduled to play in the semi-finals later Saturday.

Sharapova completed a career Grand Slam in June by winning the French Open, but Williams beat her for the eighth consecutive time.

Top-seeded Victoria Azarenka of Belarus won the bronze, beating No. 14-seeded Maria Kirilenko of Russia 6-3, 6-4. Sharapova's loss allowed Azarenka to retain the No. 1 ranking.

American Jamie Lynn Gray won the Olympic gold medal in women's 50-metre three-position and set two Olympic records along the way.

Gray's final score was 691.9, topping the 690.3 mark set by China's Du Li at Beijing in 2008. She clinched gold on her final shot with a 10.8 -- just 0.1 off what would have been perfect.

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Serbia's Ivana Maksimovic won the silver, 4.4 points back. Adela Sykorova of the Czech Republic was third, 8.9 points behind Gray.

Gray's qualifying score was 592, also an Olympic record, besting the 589 set by Poland's Renata Mauer-Rozanska at the 1996 Atlanta Games.

These are Gray's second Olympics. She was fourth in air rifle and fifth in three-position rifle at the 2008 Beijing Games.

Italy's Jessica Rossi won the gold medal in women's trap shooting, missing just one of 100 shots to set a World record.

Rossi was 75-for-75 in the qualifying rounds. Her lone miss came on the 18th shot of the 25-shot final.

Rossi's overall 99 topped the former overall world mark of 96 by Zuzana Stefecekova of Slovakia in 2006, and her qualifying score of 75 was one better than the 74 by Victoria Chuyko of Ukraine in 1998.

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The former Olympic records were an overall 91 set by Finland's Satu Makela-Nummela in 2008 and a qualifying 71 by Daina Gudzineviciute of Lithuania at the 2000 Sydney Games.

After her final shot, Rossi wrapped herself in the Italian flag, while three other competitors were preparing for a tiebreaker to decide the silver and bronze spots.

Zuzana Stefecekova eventually won the silver medal, topping bronze-medalist Delphine Reau of France in the shoot-off. Alessandra Perilli of San Marino also made the tiebreaker but was the first eliminated, meaning her nation — which has appeared in the Olympics since 1960 -- is still awaiting its first medal.

The clock couldn't separate Nicola Spirig and Lisa Norden after two hours of lung-bursting effort in the women's triathlon .

At the end of a grueling race through Hyde Park - a 1,500-metre swim, a 43-kilometre (26.7-mile) bike ride and a 10-kilometre run -- Switzerland's Spirig won gold in a photo finish.

Incredibly, both athletes recorded the same time: 1 hour, 59 minutes, 48 seconds.

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In the end, Spirig held off a late charge by a surging Norden through the final few meters in one of the best triathlon finishes ever. The Swiss just thrust out her hips and upper body to win as the pair broke the tape together.

"Crossing the finish line I had a feeling that I had won but I wasn't sure," Spirig said. "I needed an official to tell me and it took a few minutes."

Both athletes celebrated. But only after they'd fallen to the ground, totally exhausted, alongside bronze medal winner Erin Densham of Australia following the sprint to the line.

After the initial uncertainty -- and a few minutes of high drama -- Spirig was declared the winner by the tiniest of margins on the photo finish.

It was Switzerland's first medal at the London Games.

Britain successfully defended its Olympic rowing title in the men's four by beating big rival Australia to the gold medal at Dorney Lake.

The crew of Alex Gregory, Pete Reed, Tom James and Andrew Triggs Hodge secured Britain's fourth straight Olympic victory in the event in dominant fashion, leading from start to finish to cross in 6 minutes, 3.97 seconds. Australia was a half-length behind in second and the United States took the bronze.

Britain, the reigning world champion, maintained its dominance of the discipline that stretches back more than two decades to the days of rowing greats Steve Redgrave and Matthew Pinsent.

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The gold was Britain's seventh medal of the regatta - and third gold - to surpass its total from Beijing four years ago, making it the country's biggest rowing haul in the modern era.

Their victory also denied Australia's Drew Ginn a fourth gold in four Olympic Games - a feat that would have been a first for an Australian.

Triggs Hodge, the British stroke, repeatedly punched the air after sealing victory and the four crew members got in a huddle on the jetty after climbing out of the boat.

The Australians and the British then embraced, a friendly ending to months of mind games and trash talk by the rival crews.

Ginn said Australia would turn the final into a "drag race," going out hard from the start, but it was Britain which took the early lead by 0.3 seconds after 500 meters.

The cushion was 0.6 seconds at the 1,000 and 1,500-metre markers and Britain held on comfortably as they were roared home by the crowd, winning by 1.22 seconds.

The bronze for the U.S. crew of Glenn Ochal, Henrik Rummel, Charles Cole and Scott Gault was the country's first medal in the event since the Barcelona Games in 1992.

In his final feat of athleticism at the Olympics, Bob Bryan caught his brother.

Mike Bryan leaped into his twin's arms after they completed a career Golden Slam by winning the gold medal in doubles Saturday, beating Jo-Wilfried Tsonga and Michael Llodra of France 6-4, 7-6 (2).

"For those moments, you don't plan them," Mike said. "I usually jump, and he usually holds me."

"That's the longest we've hugged," Bob said. "We've spent 50,000 hours together, and probably 30,000 on the court, working our butts off to get here. That hug right there was a culmination of it all."

The Americans, who are three-time Olympians, won the bronze in 2008. They've won 11 major titles together and finished 2011 ranked as the No. 1 doubles team for the seventh time in nine years.

Sandra Perkovic of Croatia has won the women's discus throw at the London Olympics with a national record of 69.11 meters.

The 22-year-old Perkovic, who tested positive for methylhexanamine last year and served a six-month ban, took the lead in the second round Saturday with a mark of 68.11 and then improved it by one meter in the third round.

Darya Pishchalnikova of Russia took the silver at 67.56. She won the silver at the 2007 world championships but had the medal stripped in a sample tampering scandal and was banned until April of 2011.

World champion Li Yanfeng of China only had two successful attempts, but her first at 67.22 was good enough for bronze.