Amanda Nunes returns to the cage to face Felicia Spencer in the main event of UFC 250 on Saturday night. Nunes, the reigning UFC women's bantamweight and featherweight champion, has established herself as the greatest woman to ever compete in mixed martial arts. As such, the headlines surrounding the June 6 clash from the UFC APEX in Las Vegas have surrounded Nunes and her assumed victory.

In the case of the challenger Spencer, that means showing up to the featherweight title bout as a massive underdog both at the betting window as well as in the minds of fans and media. It should be remembered, however, that Spencer is a former Invicta FC champion and has only suffered one loss as a professional -- a fight where she was one of the few women to survive a fight with Cris Cyborg to the final bell.

In a sport that feels as though anything can happen, at times, Spencer does have a narrow path to victory. Here are three keys for Spencer to focus on as she tries to pull off one of the biggest upsets in UFC history over arguably the greatest female fighter ever. 

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1. Constant pressure

Germaine de Randamie laid out the beginning stages of a strategy to combat Nunes. It wasn't a successful one because Nunes is simply the more-skilled fighter, but she was able to do some decent work on the feet, both at distance and in the clinch. Spencer should study that clinch work and attempt to replicate the attack. Standing at distance and trading won't work out well for Spencer, but she also can't stand and wait for Nunes to initiate. In that case, Nunes will be proactive by battering her with kicks and punches.

Spencer needs to push forward, grab a body lock and try to push Nunes' back into the cage where the champ won't be able to use a Thai clinch as effectively. When the two women are standing, Spencer needs to make the fight as dirty as possible. She can't compete strike-for-strike, so she needs to employ some old-school Randy Couture tactics. When and if that pressure creates an opening, she needs to look for a takedown and try to work on Nunes from top position. Nunes' biggest weakness is fighting off her back; pressure is the path to putting her there.

2. Take advantage of Nunes' mistakes 

Circling back to the de Randamie fight, Nunes dominated from top position once she decided to start working takedowns. But she also got sloppy and was caught by upkicks, also finding herself locked in a fairly deep triangle choke. Nunes doesn't provide many openings to be finished, especially since her September 2014 TKO loss to Cat Zingano.

If Spencer is able to pressure Nunes into a takedown, she needs to not only try to maintain top position but also take advantage anytime Nunes leaves an opening while trying to escape the position. And, if Nunes is on top, if she gets overly aggressive and leaves an opening for a triangle choke or other submission -- as she did against de Randamie -- Spencer has to secure the finish. Spencer has legitimate, high-level jiu jitsu chops. She's better equipped than de Randamie to do just that -- even if it's a long shot.

3. Hope 

Not to take anything away from Spencer, who is a legitimate title contender and very good fighter, but Nunes is operating on a different level over the past few years. Matt Serra upset Georges St-Pierre; Holly Holm upset Ronda Rousey; Andy Ruiz upset Anthony Joshua. Upsets happen in combat sports, but many times those upsets require a certain unusual spark. Maybe it's distraction from outside the cage heading into the fight, maybe it's an unlikely strike landing perfectly for a knockout or maybe it's the heavily-favored champion slipping into a submission.

Spencer can win -- it's not impossible by any measure. But it is unlikely. Like many great upsets, Spencer should be hoping for that tiny moment that alters the course of history. A victory for Spencer probably doesn't come from winning rounds but comes from finding a finish. And there's nothing wrong with having a little extra hope that she can find that magic moment.

Who will win Nunes vs. Spencer, and how exactly does each fight end? Visit SportsLine now to get detailed picks on every fight at UFC 250, all from the accomplished MMA expert who's up more than $20,000 and has nailed eight straight main event winners.