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LONDON — Anthony Joshua will leave a modest apartment he shares with his mother in suburban London to go to work on Saturday. A few hours later, the 27-year-old will come home nearly $20 million richer.

British boxer Anthony Joshua, left, and Ukrainian boxer Wladimir Klitschko pose for the media at the end of a press conference in London on April 27, 2017. Matt Dunham / AP

Work on Saturday won’t be a straightforward day at the office, but a world heavyweight boxing bout with Ukraine’s Wladimir Klitschko. There will be 90,000 people watching at London’s Wembley Stadium and more than 1 million more watching at home having parted with at least $50 each for the privilege.

Regardless of who wins, both fighters take a 50 percent cut of the purse. But despite the equal share of winnings, the fight presents a classic battle of deeply contrasting backgrounds and lifestyles.

Klitschko, 41, has a Ph.D. and has worked as an adjunct professor at the University of St. Gallen in Switzerland. His fiancé is Hollywood actress Hayden Panettiere, with whom he has a daughter. His brother Vitali, in addition to being a former boxing champion, is current mayor of Kiev and one time front-runner for the presidency of Ukraine.

Alongside his brother and fiance, Klitschko addressed protesters who gathered in the Ukrainian capital in 2014 to support the ouster of then-President Viktor Yanukovych. He won gold in heavyweight boxing at the Atlanta Olympics and spent nearly 10 years as world heavyweight champion, the second longest reign in history.

In contrast, when Klitschko was fighting for Olympic gold in 1996, Joshua was 6 years old.

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A promotional video released for Joshua in the lead up his bout with Klitschko details his background — showing how different it is from his opponent's.

The video depicts how he was mixing with the wrong crowds at an early age. Living in the town of Watford just outside London at the time, Joshua said that it led his parents to send him to boarding school in West Africa as a teenager in hopes of straightening him out.

The tactic failed, and Joshua, a latecomer to boxing at 18, started some of his early fights with a gift from British prison authorities — an electronic ankle bracelet.

By 2008, Joshua was working part time as a bricklayer. At the same time Klitschko was defending his world title at Madison Square Garden.

"Can you imagine ... I'm going to fight a guy whose age is exactly ... how long I've been in boxing — 27 years. Can you imagine that? It's a pretty amazing fact,” Klitschko said at a press conference to promote the bout earlier this week.

The pair do have some things in common. Sixteen years after Klitschko won his medal, Joshua delighted home crowds by doing the same at the London Olympics — winning the gold in heavyweight boxing.

Boxer Wladimir Klitschko and actress/model Hayden Panettiere attend the 34th Annual Sports Emmy Awards Reception on May 7, 2013, in New York. Jemal Countess / Getty Images file

Joshua also has one child, a son. Their life takes place far from the glamour of Hollywood, however, and Joshua's social media posts show his son is from an off-and-on relationship with his high school sweetheart.

From a rocky start, Joshua has transformed himself into one of the more marketable athletes in the world. He says cigarettes, alcohol and petty crime are all far in the past and have been replaced by endorsement deals with Jaguar, Beats by Dre, Lucozade and Lynx, all listed on his official website.

With another decade or more in the ring ahead of him, if he can continue to attract sponsorship and earn the kind of money he’ll make this weekend, his career earnings could enter into the billions.

"I believe that Anthony Joshua will be the first billionaire fighter," former world title fighter Scott Welch told The Daily Telegraph.

"I really do believe that. Floyd Mayweather has earned $600 or $700 million, Mike Tyson earned $400-odd million 20 or 30 years ago,” Welch added.

In an interview with GQ magazine Joshua said his first aim was to overtake soccer superstar David Beckham’s career earnings of nearly $400 million to be the richest sporting Briton of all time, then Floyd Mayweather Jr.’s haul of $700 million to be the richest boxer ever.

“When I first started, the aim was to become a multi-millionaire. But now there are ordinary people, grandmas and grandads, who are worth millions just because of property prices,” he told the magazine. “So the new school of thought is that I need to be a billionaire. Being a millionaire is good but you have to set your sights higher.”

Thumbs up. From now on the nick name was made - "Mr.Billionaire" You've got to love AJ's ambitions! — Klitschko (@Klitschko) April 8, 2017

First, though, is Saturday’s bout. For Joshua it’s rather simple, “I win. I win. It's not complicated. Let's not overthink it, this isn't science. It's not rocket science, it's just a fight.”

In contrast, Klitschko declared, “I'm not Nostradamus but I feel so strongly and my obsession made me record a video last week [predicting] the outcome of the fight [on a USB stick]. This stick is going to be integrated in my robe which I'm going to wear this Saturday night — sealed.”

The robe will be auctioned with the proceeds going to a Ukrainian children’s charity he runs.