Tough one! I'd say Ohba outworks Yuri in a very close fight. Yuri's somewhat lackadaisical approach would be his downfall. Even in his earlier fights he could have been a better fighter if he fought with more fire. Ohba's chin was suspect, he was especially vulnurable in the early rounds - Yuri probably drops him a couple of times. Ohba would have survived those scary moments because of his will and composure as well as Yuri's overly measured approach.
