Anthony Joshua has claimed "sometimes the ones who are calm and chilled can bark", when speaking about Andy Ruiz during a press conference in London on Friday.
The Briton also rated Ruiz as "the best heavyweight out there".
Both boxers went face to face in London, as their three-day press tour ended, ahead of their December 7 rematch in Saudi Arabia.
Asked about again being a challenger to the world heavyweight championships, Joshua said: "It's a great mindset to have and you can't lose that. The minute you lose it, you've got to retire. You've got to be hungry.
"I had a blip. We go again. I'm not shy. No fear."
Joshua said about his upcoming opponent who took his IBF, WBA and WBO belts earlier this year: "Ruiz Jr is calm but he can fight. He is not a fake character who puts on a persona.
"Sometimes the ones who are calm and chilled can bark back, and can definitely fight."