#4. Casey O'Neill
Casey O'Neill has emerged as an ominous presence in the women's flyweight division. The Australian-born Scottish phenom has a uniquely blended accent and represents both nations. More importantly, she is a hearty competitor and could find herself in the upper echelons of the division very soon.
O'Neill currently boasts a perfect professional record of 9-0, with three knockouts and two submissions under her belt. In her most recent outing, she defeated MMA veteran Roxanne Modafferi, which saw her claim the No.13 spot in the 125-pound rankings.
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Notably, O'Neill has beaten Valentina Shevchenko's sister Antonina. 'King' finished the older Shevchenko sister via TKO last year following an impressive display of grappling and is a tough stylistic matchup for the reigning flyweight queen.
While she's still quite a few wins off a shot at gold, when she does eventually contest the belt, it has all the makings of a competitive fight.
#3. Alexa Grasso
Alexa Grasso has slowly but surely emerged as a solid contender at 125 pounds. The Mexican joined the UFC in 2016 after putting together a scintillating four-fight win streak at Invicta FC, the world's leading MMA promotion exclusive to women.
Grasso is largely known for her boxing, as is the case with most fighters hailing from Mexico. Her professional record currently stands at 14-3, with four knockout victories to her name. Even in fights where she didn't finish her opponents, Grasso displayed incredible hand-speed and technical prowess, somewhat similar to Valentina Shevchenko.
In her most recent outing, Grasso showed new wrinkles to her game, submitting perennial contender Joanne Wood in the very first round of their clash at UFC Columbus earlier this year.
Alexa Grasso sits at No.5 in the flyweight rankings and will need some high-profile wins if she is to earn a championship opportunity. Still just 28, she has all the tools and time to hone her skills before eventually squaring off with Valentina Shevchenko, who has vowed to stay atop the division for a long time.
It will take a Herculian effort, but Grasso certainly has the ability to give Shevchenko a tough fight, especially if she continues on her current trajectory.