Carl Frampton has rubbished Scott Quigg's claim that the Belfast man has been knocked out in recent sparring sessions as they prepare for the world title unification fight in February.
Quigg, 27, made the allegation at the duo's latest pre-fight news conference in Belfast on Wednesday.
"I know for a fact he has been knocked out in sparring," Quigg told BBC Sport.
However Frampton, 28, responded: "They are clutching at straws. I've never been knocked out in my life."
Bury's Quigg, the WBA super-bantamweight champion, will fight IBF champion Frampton in Manchester on 27 February.
Quigg knows he can't win - Frampton
After the duo's verbal sparring in London on Monday and Manchester on Tuesday, it was the turn of the IBF champion's home city of Belfast to sample the Frampton-Quigg road show.
Around 1,000 of Frampton's friends and fans crammed into the Europa Hotel's grand ballroom to see the two fighters - and their entourages - trade the inevitable verbal fisticuffs.
"Scott Quigg doesn't actually believe that he can win," claimed Frampton. "There are doubts there. And I know that me at 90% beats the best ever Scott Quigg."
The Englishman attempted to get under Frampton's skin with his continued insistence that the Northern Irishman has been having problems in sparring.
"I know for a fact I haven't been knocked out in sparring but that's not the case with Carl and they know that," he said. "If the shoe was on the other foot or they'd heard any rumours, they would be quick to say it but they can't."
Quigg's promoter Eddie Hearn previously fulfilled the same role for Frampton before the Barry McGuigan-managed fighter left the Matchroom set-up in May 2013.
Frampton described Hearn as "being his normal smug self" on Wednesday and also hit out at Quigg's "cocky and arrogant" trainer Joe Gallagher.
Former world heavyweight champion David Haye has been training at McGuigan's gym in Battersea in recent weeks as rumours intensify about a possible comeback and Frampton says the Englishman's presence is helping him.
"I can learn a lot from David. He has been to the very top. We can maybe learn a bit from each other," he said. "It's good having him about gym. He's a big character."