Fierro lost that 10-round junior welterweight war with Isaac “Pitbull” Cruz by unanimous decision in February 2025, but the determined Mexican rivals delivered one of the best action fights.

Their fight was so entertaining, an immediate rematch was scheduled as part of the Manny Pacquiao-Mario Barrios undercard seven months later.

Fierro had so much difficulty making weight that he was hospitalized the day they were supposed to weigh in and replaced by Omar Salcido on short notice.

Two months later, Fierro was disqualified for kicking Abraham Cordero in the groin during the third round of what was designed to be a tune-up fight October 4 in his hometown of Tijuana.

That disastrous stretch somehow led to Fierro securing another high-profile opportunity, a 12-round bout with another Mexican in junior welterweight contender Oscar Duarte on the Gilberto Ramirez-Benavidez undercard Saturday night. Duarte (30-2-1, 23 KOs) is 14-1 favorite according to DraftKings, but Fierro (23-4-2, 18 KOs) realizes he can change what has been a career-crushing nine-month span.

"I love being the underdog because when I'm the underdog, you don't know who's going to come and spoil the party," Fierro said during an open workout Wednesday at MGM Grand.

"I was the underdog against 'Pitbull' Cruz. We put on a show and it was a spectacular fight. The same is going to happen with Duarte. I'm going to go out there and prove that just because I’m the underdog, it doesn't mean that I can't be the spoiler."

Duarte dealt with a weigh-in incident of his own the last time he traveled to Las Vegas.

The Parral native was scheduled to challenge Richardson Hitchins for his IBF junior welterweight title February 21 at T-Mobile Arena.

An ill Hitchins (20-0, 8 KOs) pulled out even later then Fierro before his Cruz rematch, on the day of their fight on the Ryan Garcia-Barrios undercard, after they weighed in a second time in accordance with IBF rehydration rules.

Duarte has shifted his focus to challenging Cruz, who owns the WBC interim 140-pound championship, now that Hitchins has given up his IBF belt. Fierro naturally wants to have his rematch with Cruz rescheduled.

"[Beating Duarte is] going to put me on the doorstep to even bigger fights," Fierro said. "Keep in mind, this is a big fight already. But I'm talking about world title opportunities and things I've been looking forward to for a long time. But first things first, I got to look out for Duarte and then go from there."

The Duarte-Fierro fight will be part of a pay-per-view undercard Amazon's Prime Video and DAZN will distribute in the United States, starting at 8 p.m. ET (5 p.m. PT; $79.99). Subscribers to DAZN's Ultimate plan, which costs $44.99 per month in the U.S. and £24.99 in the UK, can view the Benavidez-Ramirez show for no additional charge.

"I'm going to go out there and put on a show, like I always do," Fierro said. "I'm going to leave my blood, sweat and tears inside the ring, in order to come out with my arm raised. I'm doing this for my hometown of Tijuana."