After Russian President Dmitry Medvedev called for an investigation into the Dec. 4 parliamentary elections believed to be rigged in favor of Vladimir Putin's party, a Russian billionaire almost as audacious as Putin himself has stepped forward to challenge him for the presidency next March. Prokhorov, who owns the New Jersey Nets and made a fortune in precious metals, counts "windsurfing, jet skiing, heli-skiing and kickboxing" among his hobbies, according to his 60 Minutes interview. Russia does like its action-hero politicians, so he seems to be starting off right. Prokhorov announced his candidacy on Monday, after the largest protests to hit Russia since Putin came to power 12 years ago broke out across the nation on Saturday. But as the national mood in Russia shifts decidedly against its longtime president-turned-prime minister, Prokhorov started out by saying he'd limit his attacks on Putin, the BBC reported. He has a very specific balance in mind, too: "Criticism [of Putin] must make up no more than 10 percent … I would like to focus on the things I would do," he said at Monday's news conference.