Kostya Tszyu vs. Leonardo Mas

Kostya Tszyu 140 lbs fought without result Leonardo Mas 140 lbs by NC at 3:00 in round 1 of 12

• Date: 1997-01-18
• Location: Thomas & Mack Center, Las Vegas, Nevada, USA
• Referee: Joe Cortez
• Judge: Ray Wheatley
• Judge: Chuck Giampa
• Judge: Bill Graham

• International Boxing Federation Light Welterweight Title (5th defending of Tszyu)
  
• Weights: 139.5 lbs (each)
• Promoter: Top Rank

Comment(s):

- Mas was dropped three times, but the final knockdown occurred on a break and he could not continue.
- Originally ruled a technical draw, but later changed by the Nevada State Athletic Commission to a no contest.