The country initially won a silver medal, which elicited a wild reaction from crowds that included Prince William. But Japan filed an appeal over the score of three-time world champion Kohei Uchimura on pommel horse, the team's last routine.
Judges spent about five minutes reviewing the score, which was ultimately revised. Japan was then awarded the silver to the chagrin of British fans, who booed and jeered the judges. Britain knocked out the Ukraine for the bronze. China took the gold.
See which countries rank with the daily Olympic medal tracker
Meanwhile, athlete Michel Morganella was expelled from the Swiss soccer team for a racist tweet he posted hours after Switzerland lost to South Korea. He was the second Olympic athlete to be eliminated from a team for posting an offensive tweet. The first was Greek triple jumper Voula Papachristou.
Team USA continued to perform well at the games as Matthew Grevers not only took the gold in the men's 100-meter backstroke but also set an Olympic record. The U.S.'s Nick Thomas took silver in the same event, and Missy Franklin got the gold in the women's 100-meter backstroke.
Best Body Types for Olympic Sports
In tennis, Venus Williams put on an impressive show as she set out for a record fourth gold medal after defeating Italy's Sara Errani, 6-3, 6-1. Younger sister Serena Williams closed out a second-round victory, beating Urszula Radwanska of Poland, 6-2, 6-3. Serena defeated Radwanska's sister, Agnieszka, in the Wimbledon final this month.
Roger Federer made only a brief appearance on Centre Court at Wimbledon, beating Julien Benneteau of France 6-2, 6-2 in less than an hour to reach the third round. Federer is still seeking his first singles medal.
History and trivia of Olympic gymnastics
The women's U.S. gymnastics team has breezed through qualifying. But Jordyn Wieber, the reigning world champ, won't have a chance to go for the individual all-around title. Instead, two other American gymnasts will go for the gold.
Wieber nearly fell off the balance beam and stepped out during her floor exercise. She was only the third-best American behind Aly Raisman and Gabby Douglas. Countries are limited to two contestants in the all-around final.
After missing qualifying for the Beijing games four years ago, it was a day American swimmer Dana Vollmer will never forget. Vollmer set a new world record in the 100 butterfly and won her first individual gold medal.
El Monte native Kim Rhode became the first U.S. woman to win a medal in an individual sport in five consecutive Olympics. Rhode captured the gold medal in women's skeet and tied the world record with a near perfect performance.
Check out photos of the 2012 London Olympics competitions
The Associated Press contributed to this report.
