Pryor by late rounds ko Pryor would keep Kostya off balance with his superior foot speed and weird punching angles. Tszyu would try to get close and do damage. Pryor would land sneaky right hands throughout. By the late rounds enough of those right hands have landed to cause cumulative damage. Pryor traps Kostya on the ropes and pours in unanswered shots until Tszyy is saved from further punishment.
So is Kostya. I wouldn't be surprised if many on here pick Tszyu, but I just can't see him beating prime Pryor. Stylistically, Kostya was similar to the Arguello Pryor faced. But, he was not as big a one punch guy, and worse defensively. He was faster than Arguello, though. I would also pick prime Chavez (at least his best at 140, which wasn't really his absolute prime), Randall, and Taylor over Kostya. Prime Roger Mayweather would have a real chance as well, popping in that straight right hand with his superior reach.
You'd favour Pryor over 15 rounds as the man was a machine. But that laser-like right hand of KT's would wear ANYONE down in a fight that long. For me, these two are the greatest fighters of this weight-class so it's had to choose one without giving it some serious thought. KT was a phenomenal fighter, though. Outstanding amateur and pro.
KT was a masterclass fighter no doubt. But we have seen in the actual ring, several fighters stand up to that KT right hand. Vince P fought an awesome fight vs KT weathering that right and stepping to the right to deliver his own. Ben Tackie survived KT not close to winning but he had a tremendous chin to absorb it for 12 rounds. And Hatton got battered to get inside but he did do it. Pryor has the recuperative abilities hes getting tagged but hes getting up. I will go with Pryor is a wild fight. Pryor took an equal and just as potent Arguello right hand for 15 rounds, showed great boxing and a fantastic workrate. Pryor cant be as reckless as the Johnson fight though. No disrespect to KT but Pryor always seems to step it up to another gear when tested. I rate Pryor as top 3 pressure fighter of all time.
Being involved with Panama Lewis and Howard Smith, whilst in the middle of cocaine habit and his misses allegedly messing around with his mate/co-manager Sly Stallone; he still managed to beat Arguello; twice! That is not bad going... As for the fight mentioned: Tszyu seems to get panned nowadays, probably because he did not live up to the initial (New Chavez) hype. But he was still an excellent fighter. That said his love of battle will probably cost in this match up; with Pryor outlasting the Aussie and winning in the championship rounds.