All eyes were on the grand arrivals of the main event, but it was an onstage staredown from a long brewing grudge match on the undercard that left fans abuzz.

Senesia Estrada and Marlen Esparza just couldn’t wait until Saturday to lay hands on one another, as the pair of unbeaten flyweights engaged in a brief shoving match during the open to the public session Tuesday afternoon at MGM Grand Garden Arena in Las Vegas, Nevada.

Their bout will take place in this very venue Saturday evening, gracing the undercard of a DAZN show topped by the light heavyweight clash between defending titlist Sergey Kovalev (34-3-1, 29KOs) and Saul ‘Canelo’ Alvarez (52-1-2, 35KOs), the reigning World middleweight champion who moves up two weight divisions for the event.

A rivalry between East Los Angeles’ Estrada (17-0, 7KOs) and Houston’s Esparza (7-0, 1KO) has been in development for nearly two years, with Saturday’s blockbuster event viewed as the perfect stage on which to settle their differences.

Estrada Esparza

The two were introduced to the crowd on hand on Tuesday, and then asked to pose on stage for an obligatory staredown. Minor trash talk ensued, with both boxers grinning while hands in their respective pockets. Things grew more tense from there, with Estrada offering a held-back shove, as if a warning shot for what’s to come.

“It's very personal, even after I win I still won't like her,” Estrada insisted. “There's been a lot of talk from her for the past two years. I do my talking in the ring.

“Saturday night, we're going to show who's really the best.”

Estrada Esparza

The onstage sequence didn’t sit well with her unbeaten foe, whose grin changed to a scowl as she raced across stage in retaliatory effort.

“I don't like her because she used my name to try to get signed before I turned pro,” claimed Esparza, who won a Bronze medal as part of the 2012 U.S. Olympic boxing team who competed in London. “Before I turned pro, she said I used to run from her in the amateurs. And when I turned pro, a lot of the promoters were asking me if that was the truth. Anyone would get mad getting their name used, and completely not the truth too.

“I just don't like her. She'll hate me even more after this. It is what it is.”

The flyweight bout is scheduled for 10 two-minute rounds. An interim title is at stake, with the winner in line to eventually challenge legendary Naoko Fujioka, Japan’s first-ever four-division titlist and reigning flyweight queen.

Jake Donovan is a senior writer for BoxingScene.com. Twitter: @JakeNDaBox