Andy Ruiz Jr demonstrated his power as he prepares for his rematch with Anthony Joshua.
The Mexican American shocked the boxing world with his seventh-round stoppage of the previously unbeaten Brit in June.
He relieved Joshua of his three heavyweight world titles in one of the sport's biggest-ever upsets.
Ruiz must now defend those titles in a rematch in Saudi Arabia on December 7.
And he posted a video showing his training is in full swing as he knocked a pad out of trainer Manny Robles' hand.
Ruiz had only six weeks to prepare for his first fight against Joshua but has had more than three months ahead of the second installment.
And the champion believes Joshua has been forced into taking the immediate rematch.
“They’re forcing him to go straight to the rematch,” said Ruiz. “I think he wanted to do something a little different, to go through a different route and then face me.
“But it is what it is, we’re fighting in Saudi Arabia and I’m excited.”
Ruiz, 29, saw Joshua up close earlier this month during their media tour of Diriyah, New York and London and says he sees doubts in him.
The Mexican feels he is questioning himself because of the way he dismantled him inside seven rounds, flooring him four times, to hand him his first pro defeat.
“We all have doubts,” he said. “But it’s our choice to overcome them.
“I got that vibe off him. His eyes are focused and all that. But deep inside we don’t know what he’s really thinking.
Ruiz has enjoyed the fruits of his world-title success and has splashed out on a new house, a Rolls Royce and expensive jewellery.
He also took a private jet to meet Mexico’s president Andres Manuel Lopez Obrador, yet insists he remains focused and hungry.
“Of course, this is all material stuff,” he said as he showed off his new glittering watch and necklace.
“But what I really want is a legacy, not just 15 minutes of fame. The main thing is that I remain humble, stay disciplined, stay training and continue to be champion.
“I don’t want to let my people down, my fans down. This is something new for me and I don’t want to give it away.”
