LONDON (CNN) -- Serena Williams of the United States completed a "career Golden Slam" at the London 2012 Games on Saturday, adding the Olympic women's singles tennis gold medal to her four tennis major titles.
Williams, playing in her third Olympics, dominated Russian Maria Sharapova 6-0, 6-1 to continue a 17-match winning streak. Sharapova was playing in her first Games.
Williams, who had previously twice won gold in doubles, claimed the singles gold on the same day twin American brothers Mike and Bob Bryan won the gold medal in men's doubles. Fellow Frenchmen Julien Benneteau and Richard Gasquet took bronze.
Williams will also seek a third gold in doubles with her sister, Venus Williams. They were set to play Russians Maria Kirilenko and Nadia Petrova on Saturday.
Also in tennis, the Team GB duo of Andy Murray and Laura Robson won through to the semifinals of the mixed doubles, also to be played Saturday, a day after Murray defeated Novak Djokovic to earn a place in the men's final Sunday against Roger Federer.
Meanwhile, Great Britain won its fourth gold medal in cycling and the world's fastest man, Jamaican sprinter Usain Bolt, got his 100-meter campaign under way on day eight of the Games.
Great Britain's women's team pursuit squad set a new world record in claiming the gold against the United States, which won silver. The British team finished in 3:14.051, some five seconds ahead of the Americans.
At the Olympic Stadium, Bolt won his heat after what he described as a poor start, he strolled in at 10.09 seconds.
He faces a challenge from teammates Yohan Blake, who has stolen some of his thunder this year and won his heat in 10.0 seconds, and Asafa Powell, who also crossed the line first in his race.
It was also a good morning for Team USA, with Justin Gatlin and Ryan Bailey getting off to a scorching start, each with sub-10 second times, while teammate Tyson Gay also won his heat.
But former 100-meter world champion Kim Collins of St. Kitts and Nevis did not run in the heats after apparently falling out with his team over seeing his wife.
The sprinter, who carried the flag for the tiny Caribbean state at the opening ceremony, tweeted: "My fans. I won't lie. Won't be running later tonight." In another tweet, he said: "Even men in prison get their wives to visit."
The St. Kitts-Nevis Times said that Collins had written on Facebook: "Hours before my 5th 100m olympic race, i now find out i cant run, all because i was in a hotel with my wife/coach."
In another bit of scandal, the International Olympic Committee announced the exclusion of Russian cyclist Victoria Baranova and provisionally suspended Colombian 400-meter runner Diego Palomeque Echavarria, pending further analysis. Both tested positive for banned testosterone, the committee said.
Elsewhere, Guatemala won its first Olympic medal ever when Erick Barrondo took a silver in the 20-kilometer race walk. China's Ding Chen won the gold.
Women's doubles badminton also came to an end with Chinese duo Tian Qing and Zhao Yunlei won gold against Japan's Mizuki Fujii and Reika Kakiiwa. China's team was in the gold medal match in place of the country's No. 1 pair, Yu Yang and Wang Xiaol. They were among eight players expelled this week for trying to lose their matches to get a better draw for future rounds.
China's Li Xuerui triumphed over her compatriot Wang Yihan to take gold in the women's singles competition, with bronze going to India's Saina Nehwal, who defeated another Chinese player, Xin Wang.
In women's triathlon, Switzerland's Nicola Spirig won the gold in a photo finish with Sweden's Lisa Norden, while Australia's Erin Densham took bronze. Great Britain's Helen Jenkins went into the race as one of the favorites but only managed fifth. Team USA's Sarah Groff came in fourth.
Plenty of action remained on Saturday's schedule, a day when 25 gold medals were up for grabs.
Jamaicans Shelly-Ann Fraser-Pryce, Kerron Stewart and Veronica Campbell-Brown run in the women's 100-meter final Saturday night, going for gold against American Carmelita Jeter.
Also on the track, double-amputee sprinter Oscar Pistorius, who runs on special carbon fiber blades and is nicknamed "The Blade Runner," came an impressive second in his heat of the men's individual 400-meter race, qualifying for Sunday's semifinals.
He is the first person to compete in the able-bodied Olympics using prosthetic legs -- and he will also compete in the Paralympics later this summer.
The four-time Paralympic Games gold medalist, whose legs were amputated below the knee when he was 11 months old because of a bone defect, has also been named in South Africa's 4x400-meter relay team.
The home crowd will be cheering on Jessica Ennis, who is seeking gold in the heptathlon after a strong start Friday.