The 2012 London Olympics kicked off Monday with gymnastics, a day after Jamaican sprinter Usain Bolt successfully defended his 100 meter title and set a new Olympic record at 9.63 seconds.

On the women's uneven bars, Russia's Aliya Mustafina won the gold medal over China's Kexin He, who won silver, and Britain's Beth Tweddle, who won bronze. U.S. teenage gymnast Gabby Douglas, who has emerged as a star of the Games, was competing for her third gold medal in the event, but only placed eighth.

Brazil's Arthur Nabarrete Zanetti won gold in the men's rings final, besting China's Yibing Chen, who finished second, and Italy's Matteo Morandi, who placed third.

In the 50-meter rifle event, Italy's Niccolo Campriani placed first, ahead of South Korea's Jonghyun Kim at second and America's Matt Emmons at third.

Later in the day, the U.S. basketball team, which barely won its game against Lithuania last week, plays Argentina, a tough team that lost to the U.S. last month by a slim 86 to 80 in an exhibition game.