The thick, sparkling ring on his right hand and the diamond-studded watch around his left wrist were indications of just how much life has changed for Andy Ruiz Jr. since he became world heavyweight champion.

It was another part of his attire that really stood out, however, when the portly Mexican came face to face with Anthony Joshua for one of the last times before their title rematch in Saudi Arabia on Saturday.

For the final news conference ahead of the fight, Ruiz chose to wear a New York Knicks jersey — yet another reminder to Joshua of that fateful night at Madison Square Garden in June when he lost his three heavyweight belts in one of boxing’s biggest shocks in years.

“That’s where I got the first victory on June 1 and that’s why I brought it,” Ruiz said, referring to his jersey. “I wore it to remind myself, ‘I’m the champ.’”

And Ruiz has really made the most of his new status over the last five months. One of his first acts was to buy a car for his mother, Felicitas, and he also showed off his lavish new home in California, replete with its fountain and pool, on his social media accounts. He had an audience with Mexico’s president, Andres Manuel Lopez Obrador, and threw the ceremonial first pitch at a Los Angeles Dodgers game.

Basically doing things he could never have imagined when he used to mix cement for his father, Andres, as a youngster and, as recently as 2017, went a whole year without even fighting following a loss to Joseph Parker in his only previous world title bout. He was disregarded as a potential champion then, mocked for his flabby frame even though his fast hands and skills pointed to a boxer with talent.

Ruiz is at pains to point out, though, that he is simply enjoying his life and not taking his eye off the ball — something Joshua says he did before the first fight.

“There’s no way I’m going to let these belts go,” Ruiz said, looking at the WBO, WBA and IBF straps in front of him. “I’m going to die trying. It’s been a roller coaster but now I’ve finally made it all this way, there’s no way I’m going to let them go.”

Ruiz knows he will be up against a different Joshua this time around. A more focused and determined Joshua, who knows he is suddenly fighting to rescue his career after being knocked down four times before the seventh-round stoppage in New York.

The first ever heavyweight title fight in the Middle East, somewhat controversially arranged amid concerns over Saudi Arabia’s human-rights record, has been called the “Clash on the Dunes.” As for Joshua, he’s labeling it “Back to 16” — a reference to his 16th professional fight when he became world champion for the first time.

He says he is likely to weigh in on Friday at about 238 pounds (108 kilograms), which would be the lightest he has fought since 2014, and has been concentrating on sparring and the “sweet science of the sport” instead of bulking up and doing weights.

He has even grown his hair into an Afro, as if he was boxing “in the ‘70s.”

“I’m punching like a horse kicking back right now … loose and heavy, rhythm and flow,” said Joshua, adding that he “didn’t lose heart or any fire in my belly” after getting beaten by Ruiz for the first loss of his professional career.

“There’s no fear in my heart, no fear in my mind,” he said. “I was asked if this would be a special moment (to regain his belts). I said, ‘No.’ I know I belong there. It’s not special. When I regain those belts, I’m probably just going to keep cool and stay focused. It’s not a time to celebrate.”

The fight will take place in the Diriyah Arena, a purpose-built venue with a capacity of 15,000 spectators that has been built in six weeks and will be taken down within two days of the bout.

No stranger to hyperbole, Joshua’s ambitious promoter, Eddie Hearn, is comparing the occasion to the “Rumble in the Jungle” and the “Thrilla in Manila” — two famous heavyweight fights from the 1970s which were held in unlikely global locations. And he is calling it a “new dawn for the sport of boxing,” predicting many more high-profile fights in this part of the world. With Joshua earning as much as a reported $70 million and Ruiz reportedly $10 million, the attraction for fighters is obvious.

Joshua isn't sure what type of atmosphere he'll be fighting in, although it is unlikely to be anything like the raucous occasions he is used to in Britain. Not that he cares, given the precarious situation his career is in.

“I’m not here to put on a show,” Joshua said, sounding all business. “I’m here to win.”

Ruiz, reveling in his status as the first fighter of Mexican descent to win a heavyweight title, has no intention of letting that happen.

“I know AJ’s going to come with a different game plan, I know he is prepared and motivated,” he said. “That’s what gives me the motivation, the edge to be more cautious. I know he lost weight, is going to try to box me around. It's my job to prevent that. I'm ready for whatever comes my way.”