Andy Ruiz

The 'Clash on the Dunes' in Diriyah was for the IBF, WBA, WBO and IBO titles.

The judges scored the fight 118-110, 118-110 and 119-109 to Joshua after 12 scheduled rounds.

"It was his night, man," said Ruiz as his six-month reign ended in the 15,000 seat arena on the outskirts of the capital Riyadh.

The decision to take the fight to Saudi Arabia had been criticised by human rights campaigners but Joshua complimented the hosts and welcomed Ruiz's suggestion that there should be a third encounter.

Joshua is trying to reclaim three of the heavyweight world titles he lost to Ruiz in June by beating the American on Sunday morning in Diriyah.

Human Rights campaigners have criticised the fight's location and urged Joshua to "speak out" about issues in the country.

"In the future maybe I can bear a different kind of flag," Joshua said.

"But at the minute it's a world championship flag. I just want to do a job."

British promoter Eddie Hearn announced the highly-anticipated sequel for December 7 a fortnight ago but Ruiz, the WBA, WBO and IBF champion, initially disputed the venue.

Reports suggest Mexican-American Ruiz has  been swayed by a larger cut of the revenue than his initial share of $15m for the mega-fight dubbed "Clash on the Dunes".

"I dethroned the king June 1st and made history becoming the first Mexican/American champion of the world," Ruiz wrote in a tweet confirming his acceptance.

Ruiz scored a seventh round TKO victory over Joshua in New York last weekend to win the WBA, WBO and IBF belts and grab control of an increasingly heated division that includes resurgent Kiwi Joseph Parker, still the only fighter to have beaten Ruiz.

There is a rematch clause and Joshua's stunned boss Eddie Hearn immediately looked to invoke that, calling for a sequel in Britain in November-December.

But Ruiz wants to cash in on his status as Mexico's first world champion in the glamour heavyweight division and has raised the idea of a home bout.

Anthony Joshua, a chiseled, towering, undefeated British world heavyweight champion with a wide grin and an easy disposition, came to Madison Square Garden on Saturday night to make his United States debut. He had talked before the fight about not just winning, but winning in style, and about the potential for a megafight down the road against Deontay Wilder, an undefeated world champion from the United States.

The pair will fight for the WBO world heavyweight title in Auckland next month.

Ruiz told Fight News that he's as studied the past fights of the 24-year-old Parker, and he's noticed that the New Zealand can't fight well going backwards.

Ruiz wasn't impressed with how the 6'4" Parker fought in his narrow 12 round unanimous decision win over Carlos Takam in May in their fight in the WBO heavyweight eliminator bout.

"In his fight against Carlos Takam he didn't really look that good, he's not good fighting backward," Ruiz said.

The fight has been confirmed for Auckland's Vector Arena on December 10 and the 24-year-old Parker couldn't be happier to see that outcome from a prolonged battle to secure the finances to make it happen.

Parker made that clear when he fronted media via a video link on Wednesday.

"Now that it is locked in and we know it is in New Zealand, that very important because we have everything set up there. It's fantastic," Parker said.

The New Zealand boxer is set to face Mexican-American Andy Ruiz for the WBO title on 10 December.

Parker's promoters Duco have been trying to secure the seven-figure sum required for the fight to happen in Auckland, but had withdrawn their bid for public money to help stage the event citing reaction from the public, media and politicians.

RNZ reports Andy Ruiz has an unbeaten run over 21 fights, with 18 knockouts. The New Zealand boxer Joseph Parker will fight Mexican Andy Ruiz for the WBO world heavyweight title in Auckland in December.

The WBO title was vacated by Briton Tyson Fury earlier this month after revelations he was suffering from depression and drug addiction.

WBO gave the order for Parker and Ruiz to fight during its convention in San Juan, in Puerto Rico.

The bout is likely to be on 10 December.