The UFC 310 main event is a mystery story, one that will play out in a narrative genre that’s not so much whodunit as who-is-it. Saturday’s fight pits a low-profile champion from a lower-profile weight class, men’s flyweight Alexandre Pantoja, against a challenger many U.S. fans will see for the first time, Kai Asakura. Maybe leaning into the unknown is the UFC’s way of building the suspense.

And yet, there’s an undercurrent of familiarity in this weekend’s headline matchup in Las Vegas (ESPN+ PPV, 10 p.m. ET). When Pantoja enters the Octagon, he might even feel like he’s walking into a déjà vu experience: Just like last time, he will be staring across the cage at an under-the-radar challenger. In May, at UFC 301, Pantoja defended his title against Steve Erceg, who was unranked by ESPN and had barely dipped his toe into the UFC’s top 10. The champ passed that understated test by a unanimous, but highly competitive, decision.

Now Pantoja gets Asakura, who will be making his UFC debut. However, as fans across the Pacific Ocean know, the challenger is no newcomer to the fight game. The 31-year-old from Japan, a two-time former Rizin bantamweight champ with notable wins (Kyoji Horiguchi, Manel Kape, Juan Archuleta), has been competing professionally for 12 years — just never before in the United States.

As for Pantoja, who’s 34 and from Brazil, he is quietly restoring stability the flyweight division hasn’t seen since the days of Demetrious Johnson. It’s not anywhere near “Mighty Mouse”-level stability, of course, as Johnson was a champ from 2012 to 2018 — a reign of 2,142 days, the second-longest in UFC history. Johnson made a record 11 consecutive title defenses, while Pantoja will be going for just his third this weekend.

Still, if he’s successful, Pantoja (a -260 favorite to win, per ESPN BET) would join light heavyweight Alex Pereira and lightweight Islam Makhachev as the only current UFC champions with more than two defenses of the throne. He’s not a big shot like those other two, but Pantoja is building momentum and has risen into the ESPN pound-for-pound top 5.

In terms of championship credibility, Pantoja may be no more than a mini-Mouse. But to his credit, he’s not treating the 125-pound belt like a hot potato, as his predecessors Brandon Moreno and Deiveson Figueiredo did for three years. Between the summers of 2020 and 2023, Moreno and Figueiredo met four times and traded the strap back and forth, each ending the other’s short reign before either could gain steam. Pantoja finally broke the impasse with a July 2023 win over Moreno, and he’s held onto the UFC title ever since.

Will Pantoja emerge from the shadows and shine under the main event spotlight? Or will Asakura make an unbeatable first impression? That’s the marquee storyline at UFC 310, but in case it’s not dazzling enough of a showcase to entice fight fans, the promotion is fortifying the card with a terrific co-main event between undefeated welterweights, plus a couple of former champions and more. Here are five of the stories that will be intriguing to watch.

1. Zero reason to miss this one

Welterweight: Shavkat Rakhmonov vs. Ian Machado Garry

Having said all those nice things about the main event, it’s the co-main I’m way more interested in. How could one put anything above an unbeaten-vs.-unbeaten matchup with both participants high in the rankings? Rakhmonov (18-0), ESPN’s No. 3 at 170 pounds, was supposed to be in the headline bout, challenging Belal Muhammad for the welterweight title. But the champ suffered an infection in training, and rather than wait it out, Rakhmonov opted to fight on against the No. 6 ranked Machado Garry (15-0). Taking this fight is a bold move by both men, especially Rakhmonov, who because of his 18 finishes in 18 fights, has come to be viewed as a champion-in-waiting. I’m glad he took the risk. No disrespect to Muhammad, but even with no belt on the line, this is a more appealing matchup than that title scrap would have been. It’s a rarity to see a collision of two high-level MMA fighters who do not know what it feels like to lose.

2. Something new to freshen things up

Men’s flyweight championship: Alexandre Pantoja (c) vs. Kai Asakura

Some might consider it a negative that the UFC is handing a title shot to a fighter making his debut. I probably would have shared that sentiment if Asakura were cutting in front of a clear No. 1 contender, but no 125-pounder is getting the Tom Aspinall treatment here. Asakura’s spot could have gone to a different Japanese fighter if Tatsuro Taira — ESPN’s No. 1 ranked fighter under 25 — had not had his unbeaten run ended by Brandon Royval in October. The title fight couldn’t shift to Royval, though, because he already had two shots at Pantoja. Brandon Moreno has had three. Pantoja totally owns this division, and that has driven the UFC to think outside the octagonal box and bring in mystery man Asakura. And I’m way more intrigued by the unknown than I would have been by continuing the endless parade of rematches that used to suck the life out of the 125-pound championship picture.

3. They can’t keep their hands off each other

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How Aljamain Sterling relates chess to his fighting

UFC bantamweight champion Aljamain Sterling fell in love with chess after giving it a try during the pandemic.

Featherweight: Movsar Evloev vs. Aljamain Sterling

For fans of the co-main’s unblemished matchmaking, here’s a pairing of a former champion and an undefeated fighter. Sterling, who moved up to 145 pounds after his bantamweight reign ended last year, will have his wrestling tested by Evloev (18-0), who has landed multiple takedowns in all but one of his eight UFC fights. Every one of those fights went to decision, by the way, which might satisfy grappling nerds but will unnerve those who live for the exhilaration of a knockout or submission. I’ve seen Sterling finish some top-shelf guys (TJ Dillashaw, Cory Sandhagen), so perhaps this one won’t come down to us listening to Bruce Buffer read off scorecard numbers that we’ll probably think should be reversed. Don’t expect a brawl, but fighters this good are worth watching go to work. (The other ex-champ in action at UFC 310: Chris Weidman, who faces Eryk Anders.)

4. No landing spot for a big leap forward

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Ciryl Gane overpowers Serghei Spivac with a flurry of fists for a TKO

Ciryl Gane overwhelms Serghei Spivac with a flurry of fists and knees to win by TKO.

Heavyweight: Ciryl Gane vs. Alexander Volkov

After his no-show performance in a two-minute submission loss to Jon Jones early last year, Gane resuscitated his reputation to some extent with a second-round TKO of Serghei Spivac in September 2023. But he’s been idle for over a year. Even though it’s not his fault — this bout was scheduled for October until Volkov injured his knee in training — any momentum the big Frenchman had has hit a brick wall. It’s unclear whether a win here would carry either man forward. The division is at the mercy of Jones, and all the Gane-Volkov winner can do is tread water until his time comes. Keeping one’s head above water can be a challenge in a choppy heavyweight sea filled with sharks with big teeth and bigger fists.

5. Do not stand up under any circumstances

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Gracie fights for himself, his family’s legacy

Kron Gracie discusses the significance of a Gracie winning in the UFC again, and the people he fights for in his career.

Featherweight: Bryce Mitchell vs. Kron Gracie

Feeling lucky? This one is a coin flip: It could be “get ya popcorn ready” or it could be stale bread. Gracie comes from the family lineage that put MMA on the map — his Uncle Royce won the UFC 1, 2 and 4 one-night tournaments — and, more than three decades later, has not evolved beyond a clan of jiu-jitsu specialists. The last time Gracie fought, in a lifeless loss to Charles Jourdain a year and a half ago, UFC CEO Dana White commented afterward that he looked like something “out of a time capsule in 1995.” It was not a compliment, despite coming from the guy whose job is to sell us on his fighters. Now, though, Gracie is matched up with a fellow grappler in Mitchell. If this contest is determined by the one dimension where both men excel, it could be fun to watch while eating our pretzels. If they start boxing instead, it would be a good time to go to the kitchen and grapple a sandwich into submission.