South African Oscar Pistorius sprinted into Olympic history Saturday in London, becoming the first amputee runner to compete in the Games.

Pistorius, who wears special prosthetics on both legs, finished second in a preliminary heat of the men's 400 meters. He qualified for the semi-finals.

He was born without fibulas – the outer bones in the lower legs.

Elsewhere, it was a big day in tennis for the United States.

Serena Williams clinched her first Olympic singles gold medal. She dominated Russian Maria Sharapova in the women's final, 6-0, 6-1. Williams is only the second woman to win an Olympic singles title and all four tennis majors.

In men's doubles, twins Bob and Mike Bryan won the gold medal by beating France's Jo-Wilfried Tsonga and Michael Llodra.

The Bryan brothers have won 11 grand slam titles together.

China, which has been running even with the U.S. in the total medal count, had a memorable day in badminton.

Li Xuerui left no doubt she is the best women's badminton player in the world. She beat world champion Wang Yihan in an all-Chinese final. In doubles, China's Tian Qing and Zhao Yunlei won the women's gold medal.