Olympics: Phelps to bow out in medley relay

London: An era of unprecedented sporting domination comes to an end at the London Olympics on Saturday, when Michael Phelps swims his last competitive race.

Phelps is heavily favored to add one more gold to his collection of 21 Olympic medals, 17 of them gold, when he swims the butterfly leg of the 4x100 medley relay, a race the Americans have never lost.

The 27-year-old swam his first Olympics in Sydney 12 years ago and is retiring after London.

At the All England Club, Maria Sharapova and Serena Williams will both be playing not only for a gold medal, but a so-called Golden Slam. Each is seeking a first Olympic title to add to their career majors.

Williams said she was more concerned with winning another medal for the American Olympic team, than for adding to her list of titles.

"Whether I win or lose, that's not the big deal," Williams said. "The big deal for me, USA is guaranteed another medal. I'm guaranteed to just go out there tomorrow and have fun. That's all I can do."

The Olympic women's doubles badminton tournament, marred by a match-throwing scandal this week, ends Saturday with the final between a Chinese and a Japanese pair.

Earlier this week, another Chinese pairing, along with two teams from South Korea and one from Indonesia, were thrown out of the competition for attempting to throw their games to secure a better more favorable draw in knockout play.

In the second day of athletics, local favorite Mo Farah runs in the 10,000 meters against stiff competition including Kenenisa Bekele of Ethiopia and another British gold medal candidate, Jessica Ennis, completes the heptathlon.

The women's 100-meters final will provide another indication of just how fast the track is in the 80,000-seat Olympic Stadium.

Led by world champion Carmelita Jeter's time of 10.83 seconds, seven sprinters — including defending champion Shelly-Ann Fraser-Pryce of Jamaica — ran the first round of the 100 in 11 seconds or better on Friday.

Usain Bolt also will begin the defense of his men's 100-meter crown in the first round of heats. And South African "blade runner" Oscar Pistorious will make history when he competes in the heats of the men's 400, becoming the first amputee to run in the Olympics.

Outside the stadium, in downtown London, the men's 20-kilometer walk ends with a not-very-leisurely stroll along The Mall, the broad, tree-lined avenue running between Buckingham Palace and Trafalgar Square.

Britain aims to continue its dominance on the Siberian pine boards at the Velodrome with the women's team pursuit.