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B.J. Penn & Georges St. Pierre

B.J. Penn is a former mixed martial artist and Georges St. Pierre is the current welterweight champion of the Ultimate Fighting Championship. They sparred in 2006, and St. Pierre won in a controversial split decision that guaranteed a rematch.

That contest came in January 2009 and was preceded by mutual trash talking, which Penn took literally to the ultimate degree. "I’m serious. Georges,” Penn said. “I’m going to go to the death. I’m going to try to kill you, and I’m not joking about this." But St. Pierre had the last laugh when he defeated Penn in four rounds.

The feud may have been responsible for more than just good copy. According to the Nevada State Athletic Commission, the rematch was the sixth-highest revenue-generating event in officially sanctioned MMA history, with $4,290,020 in gross sales and 13,622 paying attendees. By contrast, the original 2006 match didn’t even make it into Nevada’s top 35 gates.

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