Given the sport's unpredictability, it can be a slippery slope to assign too much meaning to a single fight in a boxer's career. When you're talking heavyweights, where one punch can end a fight at any time, it's even more difficult. 

Yet it's hard to ignore just how damaging a loss would be for former unified champion Anthony Joshua on Saturday when he looks to regain his trio of world titles against Andy Ruiz Jr. in Diriyah, Saudi Arabia (DAZN, noon ET). Given how potentially damaging his June upset loss was to his psyche and invincibility, it's also not out of bounds to suggest this weekend's result will be the defining moment of the 30-year-old Joshua's career. 

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As the biggest star in global boxing and a veritable rock star in his native England, Joshua (22-1, 21 KOs) wasn't alone in expecting his U.S. debut at New York's Madison Square Garden eight months ago against the late replacement Ruiz (33-1, 22 KOs) would go differently. One left hook to the ear, however, crippled Joshua's equilibrium in Round 3 and triggered a lengthy implosion that -- unfairly or not -- called into question whether he ever was as great as his level of popularity suggested. 

By choosing to activate his mandatory rematch clause, Joshua showed plenty of pride in doubling down on himself. But given the almost audacious fight purses he has regularly commanded fighting in front of upwards of 90,000 fans in U.K. soccer stadiums overflowing with rabid fans, many have questioned whether a second straight loss sends Joshua away from fighting for good. 

Joshua's rumored windfall of $85 million on Saturday, which played a big part in the fight being staged in a 15,000-seat outdoor stadium that was built just for this event over the past three weeks, certainly doesn't hurt that argument. But AJ has dismissed such a notion in recent days following a fight camp held at the British Embassy in Saudi Arabia that saw Joshua largely seclude himself from the eyes of the media. 

The exact state of Joshua's mentality has become the overwhelming narrative entering this fight, turning boxing writers into armchair psychologists while looking to assess which fighter should be the favorite. The oddsmakers have liked Joshua from the beginning and if one is looking for extra reasons to believe, the 6-foot-6 slugger emerged from seclusion during fight week with longer hair and an unkempt beard, suggesting a mindset less of global humanitarian and more of refocused fighter. 

Joshua also kept on-site photographers at his public workout when he unveiled a physique that was noticeably leaner than the nearly 250 pounds of sculpted muscle he typically fights at. It's a decision that Joshua had balked at the suggest of for years, but a change that was seemingly necessary given how well Ruiz, despite a four-inch height and eight-inch reach deficit, relied on his speed to break Joshua down. 

"I was asked if this [fight] will be a special moment and I said no because I know I belong there. It's not special, I've been there, I know what I'm doing," Joshua said. "When I regain those belts, I will probably keep calm and stay focused. It's not a time to celebrate, it's time to keep that challenge, mindset and find the next target, so one by one I'm picking them off. I've been doing that since I started boxing and Ruiz is just my next target on my list."

From the reveal that he sought the counsel of former rival Wladimir Klitschko to help rebuild himself mentally following the TKO defeat to each of his thoughtful responses at media events this week, Joshua has been nothing but business. And it's the word business that is most apropos in this case because of the boxing politics at play that further define why Joshua is in such a must-win situation in this fight. 

With heavyweight going through such a renaissance and fans clamoring to see the best face off against one another, Joshua had been the division's power broker given the value of his brand and the fact that he held three of the four recognized world titles. That same power helped AJ become the de facto face of the streaming app DAZN's market disruptive launch in the U.S. last year, which kicked off with Joshua's knockout of Alexander Povetkin. 

Given Ruiz's status as a fighter under the banner of Al Haymon's Premier Boxing Champions, who took the Joshua fight on five weeks' notice after Jerrell "Big Baby" Miller failed a trio of pre-fight drug tests, a loss for Joshua would be cataclysmic for DAZN. It would also potentially isolate AJ from getting a chance to fight for the belts again for a lengthy period of time, especially if Ruiz fought the winner of the Deontay Wilder-Tyson Fury rematch in February to crown the first four-belt undisputed heavyweight champion.

"As soon as I got back from New York I got that commitment back, got into shape," Joshua said. "I didn't lose any heart, didn't lose any fire in my belly, started hitting the heavy bag, preparing for this day. I'm actually really looking forward to it. No fear in my heart, no fear in my eyes. I'm just looking forward to putting on a show, and I'm confident."

The secret truth is that Joshua may end up benefitting even more when it comes to his brand. The connection he has with his followers by immediately overcoming such a devastating defeat would be bigger than he would've by staying unbeaten. Fans love a winner, for sure, but even more they desire an authentic connection with something human and real. 

Nothing is more real or applicable to life than seeing a fighter bounce back from such a public and humiliating defeat by conquering their opponent and silencing all of the doubt and inner fear that even a former heavyweight champion of the world isn't immune to. 

Joshua can look no further than his Hall-of-Fame countryman for an example of the power of redemption as Lennox Lewis twice ran back knockout defeats in title fights to do the reverse in the rematch. 

All of the chips have been pushed to the center of the table. This is Joshua's "all in" moment.