Berlin, Germany, November 3, 2007—U.S. "chess boxer" David Depto (right) makes a move while playing against German Frank Stoldt (left) during the chess boxing world championship.

Chess boxing, a sport that alternates between speed chess and boxing rounds, has grown in popularity across Europe.

To win, players must either checkmate or knock out their opponent within 11 rounds.

Local favorite Stoldt won the championship in the seventh round with a checkmate.

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