'They don't know sh*t': Ruiz hits back at critics of party lifestyle after naked sushi birthday bash

World heavyweight champion Andy Ruiz Jr. had some strong words for his critics, including Tyson Fury, who have slated the 30-year-old for what some see as a hard-living lifestyle since he dethroned Anthony Joshua in June.

Ruiz jetted out to Saudi Arabia, the location of his December rematch with former champion Joshua, for media engagements related to the forthcoming 'Clash on the Dunes', but before that began the Mexican-American champion had some harsh words for his detractors.

Ruiz was the source of controversy in August after footage from his 30th birthday party emerged which showed the boxer celebrating in the company of YouTube personalities Jake and Logan Paul, while guests gorged on sushi served by half-naked waitresses.

Tyson Fury, one of the four men currently at the top of the heavyweight mountain, was among those critical of Ruiz's celebrations in the wake of winning three of the four recognized heavyweight titles, saying that his focus on his upcoming challenge may not be quite what it should be.

"If Andy Ruiz comes in in-shape and has trained, then I think he does the same again," Fury said.

"But one thing I know is AJ trains hard and he dedicates his life to boxing. I know that Ruiz has been running around in a lot of Rolls Royces and doing a lot of TV shows, eating a lot of tacos and he's not been in the gym for two-and-a-half months.

"I've been speaking to the guys and nobody's seen him."

However, Ruiz didn't take kindly to these suggestions.

"Everyone's gonna say this and that, but at the end of the day they don't know sh*t but what they see on Instagram," he said.

"We working. I want them to sleep on me again and think I'm just partying. We coming hard."

Just less than three months remain until the rematch, which is being billed as one of the biggest bouts in recent heavyweight history. The division, which was for so long the exclusive playground of the dominant Klitschko brothers, hasn't been as wide open as it is today in a generation, as four men - Ruiz, Joshua, Fury and Deontay Wilder - tussle for the right to be called the world's best.