During a calendar year already littered with pay-per-view fights of the must-see variety, Saturday's undisputed clash between four-belt super middleweight champion Canelo Alvarez and undisputed 154-pound king Jermell Charlo stands out in its own way. 

Their 168-pound showdown headlines a Premier Boxing Champions event (Showtime PPV, 8 p.m. ET) inside T-Mobile Arena in Las Vegas as the pair of 33-year-old stars meet in this unlikely pairing. Charlo (35-1-1, 19 KOs), the twin brother of WBC middleweight champion Jermall Charlo, replaced his sibling shortly before the fight was announced. 

As we get closer to the fight, which features an action-packed PPV undercard, let's take a closer look at the biggest storylines as Alvarez (59-2-2, 39 KOs), boxing's biggest star globally, returns to Las Vegas for the fourth time in five bouts. 

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1. Jermell Charlo is not only a lion, he's a heck of a live dog

Even Alvarez said it himself when asked which Charlo brother he deems to be more dangerous (he picked Jermell). Charlo's trainer, Derrick James, has even gone as far as saying that this super middleweight championship bout is really a pairing of two junior middleweights, as a way to try and silence the understandable chatter surrounding Charlo moving up two divisions. Although it remains to be seen if Charlo can handle the punching power of the larger Alvarez, James might not be far off. Alvarez wasn't even considered a big middleweight when he initially moved up, despite going on to win a world title at 175 pounds. And Charlo, who will own advantages of four inches in height and nearly three inches in reach, has always been huge for the 154-pound weight class. Charlo's combination of speed, power and athleticism is already a potential problem for Alvarez but when you add in Charlo's boxing IQ and the daring nature that has led him to knockout wins in both title rematches he has accepted (Tony Harrison, Brian Castano), it's clear that Alvarez will need to be on point. 

2. Canelo Alvarez has promised a return to form

Alvarez looked outright unbeatable when he stopped Caleb Plant in late 2021 to become the first four-belt undisputed king in 168-pound history. But his next three fights saw Alvarez looking uncharacteristically human, which had many wondering if 18 years of mileage as a professional has caught up with him. In Alvarez's defense, he was nursing a lingering left hand injury that prevented him from training hard ahead of a loss to light heavyweight titleholder Dmitri Bivol and consecutive decision wins over Gennadiy Golovkin (in their trilogy) and John Ryder. Alvarez recently had surgery but will make a quick four-month turnaround to fight Charlo. As far as excuses go, Alvarez's make sense to explain why he hasn't looked as sharp or dynamic in recent fights and has promised to remind everyone just how great he can be in the first of a new three-fight deal with PBC. 

3. Charlo has more questions to answer than just weight

Alvarez remains nearly a 4-1 betting favorite, which likely can be attributed most to the daring gamble Charlo is making by moving up two divisions to fight one of the best in the world without a tune-up bout. But let's not forget what else Charlo must overcome: ring rust. Charlo replaced his brother Jermall, who hasn't fought in two years due to mental health challenges and ultimately decided he couldn't be ready in time mentally for Alvarez. But Jermell must also overcome both injury and his own inactivity as he returns to the ring for the first time in 16 months due to a broken hand he suffered in training last December that twice postponed undisputed showdowns against Tim Tszyu. Charlo ultimately chose to pass up Tszyu in favor of the last-minute offer for Alvarez, which could change the fortunes of both his career and personal life with a victory. But still, these are less than ideal circumstances for Charlo to undertake ahead of such a dangerous and important fight. 

4. Extreme risk brings the potential of extreme reward for Charlo

While this superfight might feel like just another in such a decorated career filled with them for Alvarez, Saturday is undoubtedly the biggest fight in Charlo's career. In fact, the native of Houston has recently said his entire pro career has been about chasing Alvarez for a big fight. And it's hard to argue just how much the spoils of victory could do in terms of catapulting Charlo to both global stardom and a Hall-of-Fame ending. Should he pull the upset, Charlo would join Terence Crawford as the only male boxers to become undisputed champions in two divisions during the four-belt era. A loss to Alvarez, would still likely send Charlo back to 154 pounds to defend his titles in huge fights against Crawford or Tszyu. A victory, however, could kickstart a run of incredibly massive fights at 168 pounds, which has quietly become the sport's most exciting division. Should Charlo defeat Alvarez, he would likely have to do it a second time. From there, super middleweight fights against David Benavidez, David Morrell Jr., Caleb Plant and even Crawford could become massive events. 

5. The Canelo-Charlo undercard is as deep as it's explosive

For any hard-core boxing fans who remember the glory days of Don King PPV undercards in the 1990s, this weekend's fare is of the same ilk. All-action junior middleweights Jesus Ramos Jr. and Erickson Lubin square off in a crossroads slugfest that could create a future viable opponent for Charlo. Then there is an interim WBC welterweight title bout pairing former champion Yordenis Ugas and Mario Barrios, with the likelihood that the winner could secure a huge fight next against the likes of Jaron Ennis or Keith Thurman. Twenty-year-old middleweight prospect Elijah Garcia will also take another step up in terms of competition when he faces Armando Rezendiz. In addition, the free preliminary action featured on Showtime's Countdown show before the PPV will feature unbeaten heavyweight contender Frank Sanchez, former light heavyweight titleholder Oleksandr Gvozdyk and former U.S. Olympian Terrell Gashua in separate bouts.