Key dates: Aug. 5 to 7, medal matches Venue: ExCel Exhibition Centre Big story: Reigning gold medalist Mijain Lopez of Cuba returns to both defend his title and avenge a stunning loss at the 2011 world championships. Arguably the most dominant wrestler in the past decade, Lopez seemed unstoppable after the Beijing Games as he won back-to-back world titles in the 264-pound class. He showed signs of weakness at last year's world championships in Istanbul, Turkey, where hometown favorite Riza Kayaalp beat him in the finals. The idea that a new heavyweight champion could be crowned in London would have been unimaginable just a year ago. Top U.S. prospects: Justin Lester, who briefly quit the sport after failing to make the 2008 Olympic team, is considered the United States' best shot at a medal in the 145-pound class. Dremiel Byers, after a seventh-place finish in the heavyweight class in Beijing, is also a medal possibility. Spenser Mango could find himself on the medal stand if he wrestles up to his potential in the 121-pound class. Others to watch: Much like the freestyle event, Russia and Iran could bolster their countries' medal counts in Greco-Roman. Roman Vlasov of Russia, the reigning world champion at 163 pounds, has seemed unstoppable since late 2011 and has won seven consecutive international events. Saeid Mourad Abdvali, the only past world champion on Iran's squad, has dominated the 145-pound class in recent years. His teammate Hamid Sourian Reihanpour has won every title his sport offers including five world championship titles -- except Olympic gold. Little-known fact: American wrestler Ellis Coleman (above) -- who became an Internet sensation last year after a video of his now-famous "Flying Squirrel" move hit YouTube -- learned the move from his brother, Lillashawn, who initially called the stunt "The Gift of God."
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