1997-01-18 Kostya Tszyu tdraw 1 Leonardo Mas, Thomas & Mack Centre, Las Vegas, Nevada, USA - IBF
1997-01-18 Kostya Tszyu nd 1 Leonardo Mas, Thomas & Mack Centre, Las Vegas, Nevada, USA - IBF. Referee: Joe Cortez. Classified by the IBF as a no-decision result, the fight came to abrupt halt after a big Tszyu (139) left hook sent Mas (139), who had already been decked twice, to the floor just on the bell ending the first round. It was then announced that due to an unintentional illegal blow, the challenger was unable to continue.