American swimmer Michael Phelps concluded his illustrious Olympic Games career on a high note Saturday when he won his record 18th gold medal, and 22nd medal overall, as a member of the 4X100-meter medley relay.

It was Phelps' third gold medal in the 4X100-meter medley relay and a perfect way for the swimming legend to end his London 2012 Olympic Games. He finished with twice as many gold medals as any other Olympian, making a strong argument as the greatest Olympian of all time.

Melissa "Missy" Franklin, who could eventually be Phelps' female equivalent, won her fourth gold medal of the Olympics as a member of the women's 4X100-meter medley relay. Franklin got the Americans off to a fast start with the 100-meter backstroke, and she was backed up by Rebecca Soni in the breaststroke, Dana Vollmer in the butterfly, and anchor Allison Schmitt in the freestyle.

The American team set a new world record of 3 minutes, 52.05 seconds, besting a record set by China in 2009. Each woman competing in the relay had won an individual gold medal of her own, signaling to some that this quadrant could dominate the swimming world for years to come.

In tennis news, American Serena Williams easily handled Maria Sharapova on the way to her first individual gold medal. Williams defeated Russian Maria Sharapova. 6-0, 6-1, to win the title on the familiar grounds of Wimbledon.

The Olympic gold gives Williams the so-called Golden Slam because she had already won the four major tennis titles.

The Bryan twins, long considered the top men's doubles team in the world, finally got their elusive Olympic gold medal. The American Bob Bryan and Mike Bryan defeated the French Michael Llondra and Jo-Wilfried Tsonga, 6-4, 7-6 (2), to win the gold after coming up short in Athens and Beijing.

After winning 11 career Grand Slam titles, the Bryans told the International Business Times before the Olympics that a gold medal would be the centerpiece of their trophy case.

In track and field, Jamaican Shelly-Ann Fraser-Pryce barely edged American Carmelita Jeter by 0.03 second to win gold in the women's 100 meters. Jamaican Veronica Campbell-Brown finished third.

Mo Farah became the first British man to ever win the men's 10,000-meter event with a time of 27 minutes, 30.42 seconds. His training partner, American Galen Rupp, placed second, while Ethiopian Kenenisa Bekele took third.

And, in one of the most inspiring moments of the Olympics, South African Oscar Pistorius, with two prosthetic carbon legs, qualified for the semifinals of the men's 400 meters. After petitioning the Olympics to allow him to compete, he becomes the first double amputee to participate in the race.