Alexander Flores claims Joseph Parker was "gifted" his world heavyweight title in a further attempt to get under the Kiwi's skin ahead of their clash in Christchurch next Saturday.
Parker won the WBO world title when outpointing Flores' American-Mexican countryman Andy Ruiz in Auckland two years ago.
Ruiz appeared up on points before Parker finished strongly and was awarded a majority decision victory.
Ruiz claimed he won, as did several of Parker's subsequent opponents, and now Flores has chipped in with his own opinion days after saying his 26-year-old opponent had stamina problems and was going to be stopped at Horncastle Arena.
"Actually, he did lose to Andy Ruiz ... obviously he was gifted that fight, we know that for a fact," Flores said in Auckland yesterday after arriving from his Los Angeles base.
"I saw the fight again recently. Don't get me wrong, it was a close fight but Andy edged it out."
Ruiz, a talented boxer with fast hands, has been sparring with Flores in preparation for the fight and will no doubt have provided his sparring partner with valuable intelligence.
Flores sees Parker as a step to bigger things - the opportunity to become Mexico's first heavyweight world champion.
He appears confident but a victory over Parker, who has lost his last two fights, would be a huge upset.
"He backs himself," Parker's trainer Barry said of Flores. "He sat in my gym in Vegas about a week ago and said, 'you know, this is not going the distance. Joe is either going to quit on his stool, or I'm going to knock him out', and I'm thinking, 'well, good on you for your confidence but Anthony Joshua couldn't do it and Dillian Whyte couldn't do it' and we know this guy isn't a Joshua or Whyte."
Flores has won 17 of his 19 professional bouts but has never faced a boxer of Parker's calibre.
"Joseph has more experience than me on his record but experience comes from sparring, too," Flores said. "When you are sparring with top contenders and world champions, sometimes you are learning more in sparring than actual fights. We have the best heavyweights in California.
"If I wasn't confident, I wouldn't be taking this fight. I know what needs to be done and I've had great quality sparring and I don't see this fight going the distance."
The relaxed Parker will probably laugh off Flores' comments and see them for what they are - an attempt by his opponent to lift his confidence levels. For the New Zealander, the fight is an opportunity to bounce back from his disappointments this year and showcase the intense power training he has been focusing on.
He's saying little about Flores.
"I don't want to hype it up," Parker said. "I know I've got the power to knock him out. I know I've got the power to really hurt him. But I'll leave that in the ring. Sometimes when you say it and look for it, it doesn't happen. You've got to relax and let it flow naturally. When it does, that punch will land, and when it lands, it will be dangerous and he'll be crying."