LONDON -- U.S. bantamweight Joseph Diaz Jr. got the Olympic boxing tournament off to an entertaining start Saturday with a stylish 19-9 victory over Ukraine's Pavlo Ishchenko in the opening bout.

British middleweight Anthony Ogogo won the hosts' first bout, beating the Dominican Republic's Junior Castillo 13-6 to thrill a raucous crowd at ExCel.

Ireland's John Joe Nevin and Darren O'Neill also rode the crowd's cheers to opening-round victories, while Diaz became a crowd favorite after the Los Angeles-area native put on a rousing display of speed and power.

An elite pro prospect, Diaz repeatedly snapped back Ishchenko's head with uppercuts and quick strikes during a dominant third round.