UFC is ready to return to the Big Apple. After nearly two years without an event at the famed Madison Square Garden because of the COVID-19 pandemic, the promotion is back with UFC 268 on Saturday and a pair of championship rematches on the marquee, as well as a fan favorite showdown in a featured spot.

In the main event, Kamaru Usman will defend the welterweight championship in a rematch with Colby Covington. The two bitter rivals first fought in December 2019 with Usman scoring a knockout in the fifth round. The co-main event features another championship rematch when Rose Namajunas defends the women's strawweight title against Weili Zhang. Namajunas stopped Zhang with a head kick knockout in April, becoming a two-time champ in the division.

Considering the depth of the UFC 268 event, there are no shortage of storylines to sift through. Let's take a closer look at the five biggest.

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1. Usman looks to continue run at welterweight G.O.A.T. status

Not long ago, the idea of any man challenging for Georges St-Pierre's status as the greatest welterweight of all time seemed ridiculous. Even as the UFC tried to push the idea that Tyron Woodley was in GSP's league, fans weren't buying it. Then Kamaru Usman came along and started building a resume to rival that of the Canadian great. It's not just the 18 consecutive wins, 14 of which came in the UFC, it's the constant evolution of his game. Usman has gone from a wrestler to a fighter whose wrestling allowed him to have effective striking to an increasingly technical striker. Now, he's a fighter with dominant grappling, solid striking fundamentals and one-punch knockout power. As the title defenses pile up and are increasingly impressive, Usman can make a real run to dethrone GSP as the welterweight G.O.A.T.

2. Covington is fighting to remain relevant

During Donald Trump's presidency, Covington found a character that made him into a love him or loathe him star. With his ever-present "Make America Great Again" hat, post-fight interview calls from Trump and a controversial, often offensive, trash-talk game, Covington became a big name in the sport. Then, he got his jaw broken in his grudge match with Usman. Covington has only fought once since that loss, beating a badly faded version of Tyron Woodley. Between the loss, the inactivity and Trump's loss in the 2020 election, Covington has felt less and less relevant. Suffering another loss to Usman -- especially a stoppage -- would be a massive blow to any chance of him ever regaining the momentum he had coming into the 2019 clash with the champ. It's hard to carry on a character like Covington portrays when you are repeatedly flattened by your biggest rival.

3. Is this the biggest fight of Rose Namajunas' career?

Legacy is a recurring theme at the top end of UFC 268 and that's definitely true in the case of Namajunas. With her UFC 261 win, Namajunas became the first woman in UFC history to regain a championship after losing the belt. The end of her first title reign was somewhat disappointing, suffering a slam knockout against Jessica Andrade and nearly retiring as a result of the loss and mental-health issues surrounding the stress of being champion. She battled her way back to the top, however, and scored an upset knockout of Zhang, similar to how she won the title the first time with a knockout of Joanna Jedrzejczyk. As with her first title reign, Namajunas' first defense comes in a rematch of the dethroned champion. Namajunas' legacy as a two-time champion is secure, but putting together a lengthy title reign could make her legendary titleholder. In that respect, proving her 78-second knockout of Zhang wasn't a fluke by winning the rematch makes this arguably the biggest fight of Namajunas' already impressive career.

4. The dream lightweight slugfest is happening

When Michael Chandler signed with the UFC, fan imaginations began racing. One of the most common "dream fights" involving Chandler was a showdown with fellow knockout artist Justin Gaethje. Chandler knocked out Dan Hooker and found himself in a fight for the vacant lightweight championship against Charles Oliveira, a fight that saw Chandler nearly score a first-round finish to become champion before a comeback knockout by Oliveira. Gaethje hasn't fought for slightly more than a year since entering a fight with then-lightweight champion Khabib Nurmagomedov as interim champ. Both Chandler and Gaethje now sit on the very edge of title contention, needing one big win to find themselves right back in the mix. The stakes are high and the styles are perfect for a thrilling bout between wrestlers who have transitioned to knockout artists. It doesn't get much better than this.

5. Fighters in must-win spots pepper the undercard

Former lightweight champion and multi-time featherweight title challenger Frankie Edgar is 1-3 in his four most recent fights. Former lightweight title challenger Al Iaquinta is 1-3 in his four most recent fights. Former blue-chip prospect Edmen Shahbazyan has lost his two most recent outings. These three men all are facing nearly must-win situations on the undercard. Edgar has reached the highest highs of the sport and is winding his career down, whether he'd like to admit it or not. But a fighter like Shahbazyan needs to show the ability to grow from losses or be relegated to "remember that guy?" posts on the Internet. His lack of cardio and grappling has been exploited twice in a row and a loss to Nassourdine Imavov would be very hard to bounce back from.

Who wins Usman vs. Covington 2? And what other picks do you need to see for a parlay with a payout of better than 8/1 ? Visit SportsLine now to get detailed top picks on UFC 268, all from the insider who's up nearly $9,200 on MMA picks in the past year, and find out.