The 29-year-old took to the streets of California, where he was born, in an open-top car to celebrate winning the IBF, WBA and WBO titles with a seventh-round stoppage victory at Madison Square Garden.
The Mexican-American boxer returned to the city of Imperial for the parade held in his honour and told reporters he was sure he could get the better of Joshua once again.
"The rematch is going to be the same. I am going to be more prepared and more ready," he said.
"I know his flaws. I can do a lot better. The only thing that he can do is just run around, he's not good at boxing."
Joshua was on the receiving end of one of the biggest shocks in the history of heavyweight boxing on his United States debut on June 1.
He was knocked down twice in the third round and twice more in the seventh, forcing referee Mike Griffin to stop the contest.
Joshua's promoter Eddie Hearn announced days after the fight that the contracted rematch clause had been triggered and the second fight will take place in November or December.
"People thought I wasn't going to do anything, I was too big, too overweight," Ruiz Jr added. "I don't want to say all the things I am going to change.
"There is going to be a lot of changing, I am going to come at a better weight this time. It's going to be a hell of a fight."
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