ONTARIO, California – Armando Resendiz’s relentlessness enabled him to produce the biggest win of his career Saturday night.

The determined Mexican middleweight upset Jarrett Hurd by technical knockout in the co-feature of a “Showtime Championship Boxing” tripleheader at Toyota Arena. Hurd entered their Showtime co-feature as a 5-1 favorite, but Resendiz rocked him with numerous power punches and eventually opened a huge, grotesque gash on the left side of Hurd’s upper lip.

Hurd wanted to continue, but a ringside physician instructed referee Ray Corona to stop their fan-friendly slugfest five seconds into the 10th and final round because Hurd’s cut was too dangerous for him to proceed.

Resendiz improved to 14-1 and recorded his 10th knockout. He also atoned for a surprising 10-round, unanimous-decision defeat to underdog Marcos Hernandez in September 2021 at The Armory in Minneapolis.

Hurd (24-3, 16 KOs), a former IBF/IBO/WBA 154-pound champion, lost inside the distance for the first time in his 10-year, 27-fight professional career.

Hurd had his moments in their action-packed battle, but he ultimately couldn’t overcome Resendiz’s pressure and volume punching. Judges Rudy Barragan (87-84), Edward Hernandez Sr. (89-82) and Dr. Lou Moret (87-84) all had Resendiz ahead through nine rounds.

The 32-year-old Hurd hadn’t boxed before Saturday night since Luis Arias upset him by split decision in their 10-rounder on the Floyd Mayweather-Logan Paul undercard in June 2021 at Hard Rock Stadium in Miami Gardens, Florida. He was an 8-1 favorite over Arias (20-3-1, 9 KOs) and dropped the underdog during the ninth round, but Hurd lost on two scorecards (95-94, 93-96, 93-97).

Hurd planned to return on the Gervonta Davis-Hector Luis Garcia undercard January 7 in Washington, D.C., but he suffered a punctured ear drum during sparring that further delayed his return. He weighed as much as 218 pounds during his long layoff, but Hurd stepped on the scale at 159¼ pounds Friday.

In the round before the stoppage, Resendiz hammered Hurd with power punches in the final minute of the ninth round. Hurd bled badly from his nose and mouth, and was noticeably fatigued, but he showed a huge heart by slugging it out with Resendiz during that difficult round.

Resendiz pressed the action again during the eighth round, when Hurd appeared fatigued from trying to fend off his aggressive opponent.

Resendiz blasted Hurd with a right hand that knocked Hurd into the ropes with just over 1:20 on the clock in the eighth round. Another Resendiz right landed several seconds later as Hurd tried to move away from him.

Resendiz rocked Hurd with right hands, including an uppercut, toward the end of the seventh round.

Hurd knocked Resendiz off balance with a right hand with about a minute to go in the seventh round. Resendiz landed a right hand about 35 seconds into the seventh round, which made Hurd hold him.

Hurd continued to land flush punches in the sixth round, but he couldn’t keep Resendiz from coming forward. Hurd blasted Resendiz with a right hand that connected with just under a minute to go in the sixth round, but Resendiz fired back with power punches of his own.

Hurd then switched to a southpaw stance late in the sixth round and promptly clipped Resendiz with a right uppercut. Resendiz tapped his chin with his glove and implored Hurd to hit him again.

Hurd landed a straight right and a left hook a few seconds before the fifth round concluded.

Resendiz’s right hand on the inside connected with just over 30 seconds remaining in the fifth round. A right hand by Hurd stopped Resendiz in his tracks a little more than 40 seconds into the fifth round.

Hurd and Resendiz traded right hands barely a minute into the fourth round. They continued to exchange on the inside for the remainder of the fourth round, a stretch when both boxers landed hard right hands.

Resendiz went toe-to-toe with Hurd throughout the third round, when Hurd landed a right hand that moved Resendiz backward with about 40 seconds left in it. Resendiz’s left-right combination later backed up Hurd with just under 20 seconds on the clock in the third round.

Hurd blasted Resendiz with a right uppercut a couple seconds before the second round ended.

A right uppercut by Hurd rocked Resendiz with just under 1:10 to go in the second round, but Resendiz soon fired back with hard shots of his own. Hurd’s left hook snapped Resendiz’s head back 12 seconds into the second round.

A right hand by Resendiz made Hurd reset his feet with 20 seconds to go in the opening round. Corona sternly warned Resendiz with just under a minute to go in the first round for leading with his head.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.