Liam Williams has vowed to punish Liam Smith in the belief a head-butt from his rival cost him a dream fight with his "hero" Miguel Cotto.
He has also vowed he will learn from his mistakes after revealing "s*****" scales led to him coming in two pounds underweight when they first fought in April.
Williams and Smith enter Saturday's rematch at Newcastle's Metro Radio Arena hoping to secure a shot at the WBO light-middleweight title in 2018, by which time the great Cotto will have had his final fight.
The Puerto Rican has vowed to retire after fighting Sadam Ali in New York's Madison Square Garden next month, and Williams believes that that would have been him but for Smith's intervention.
He was comfortably outboxing Smith when the Mancunian head-butted him in the ninth round of their fight for the interim title, and won via stoppage when Williams was forced to withdraw because of a deep cut after what was ruled an accidental clash of heads.
Until then that performance had been the finest of his career, and the 25-year-old Welshman said: "It's quite difficult for me to swallow: I should be world champion now, lining up to fight Cotto.
"But it's pointless going over and over it. I've taken that on board now: I believe I'm going to get a good win this Saturday, so good things are going to come my way anyway.
"That superfight being against somebody I've looked up to for many years, my hero. Somebody I've always looked up to. All of that's disappointing. But I'm just focusing on getting that win on Saturday night; at this point, nothing else matters to me.
"I did start to feel the pace; in the ninth round he started turning up. Last time he came in almost four pounds heavier than me. I believe that played a big part.
"I had s***** scales in the (hotel) room. It turned out they were wrong. I saw I was two pounds overweight but I was actually bang on the weight, so I came in two pounds underweight. That's nobody's fault but my own."
Former WBO champion Smith, 29, has repeatedly accused Williams of using the cut as a way out of a fight in which the Welshman was tiring and he was starting to improve.
The only defeat of his career came against Mexico's Saul Alvarez, but he says he is again willing to fight with his head.
"I'm not denying it was deliberate; we were in a fight, it was heat of the moment," he said.
"I've seen worse cuts before that cut and worse cuts since. You've just seen Carlos Takam and Jamie McDonnell wanting to carry on; Liam did not want to carry on.
"I'm a fighter, and if Liam wants to stick elbows in, and heads on me, be prepared for it right back."