Munguia became champion in a second division because he outboxed Armando Resendiz and won their 12-round championship clash by unanimous decision on the David Benavidez-Gilberto Ramirez undercard at T-Mobile Arena. Tijuana’s Munguia defeated Resendiz by scores of 120-108 (Glenn Feldman), 119-109 (Max DeLuca) and 117-111 (Eric Cheek) and won the WBA super middleweight title from his fellow Mexican.

With Alvarez shouting instructions and cheering him on from ringside, Munguia – who now works with Alvarez’s career-long trainer, Eddy Reynoso – boxed effectively, often off his back foot, against an aggressive Resendiz.

The crowd booed several times when Munguia moved rather than engaging, but his safer, smarter strategy served the former WBO junior middleweight champion well.

The improving Munguia upped his record to 46-2 (35 KOs). Resendiz dropped to 16-3 (11 KOs).

“I felt excellent throughout the fight,” Munguia said. “I listened to my corner and that turned into great results for us. Everything went exactly as we had it contemplated before the fight. I wanted to KO him, but everything was outstanding.

“I had Resendiz against the ropes. I was on the verge of knocking him down in that last round. We tried our best to knock him out, but it wasn’t meant to be and the win was ours.”

Munguia, 29, and Resendiz, 27, both ended long layoffs in the co-feature before Benavidez challenged Ramirez for his WBA and WBO cruiserweight titles.

Munguia fought for the first time since last May 3, when he avenged his shocking knockout loss to Bruno Surace by winning their rematch unanimously on points in Riyadh, Saudi Arabia. The Voluntary Anti-Doping Association detected an adverse finding in one of Munguia’s performance-enhancing drug tests after he defeated Surace, but he was cleared of wrongdoing by the British Boxing Board of Control, which regulated the event.

Munguia told The Ring that his false positive result for testosterone metabolites was triggered by a contaminated supplement.

Resendiz returned 11 months after he produced The Ring’s “Upset of the Year,” a unanimous points victory over former IBF champ Caleb Plant on May 31 at nearby Michelob ULTRA Arena. Plant was a 20-1 favorite to defeat Resendiz.

Almost a year later, Resendiz struggled to counteract Munguia’s movement and selective combination punching.

Munguia finally buzzed Resendiz when he landed a left-right combination that sent Resendiz stumbling backward with just under 1:10 remaining in the 12th round. Resendiz recovered and eventually threw hard punches back at Munguia.

An accurate Munguia opened up in combination on Resendiz several times during a 10th round the challenger won convincingly. Resendiz didn’t seem bothered by any of Munguia’s punches, but Munguia’s momentum was obvious in those three minutes.

Munguia rocked Resendiz with a right that knocked him backward with just under a minute on the clock in the ninth round. A hard-charging Munguia drilled Resendiz with another right that snapped his head back just before the bell sounded to end the ninth.

Resendiz and Munguia traded flush shots during a spirited exchange that began with approximately 40 seconds to go in the seventh round. They took those punches well, however, just as they had done during the first six rounds.

Resendiz backed Munguia into the ropes with just under 1:20 on the clock in the sixth round and unloaded uppercuts and a left to his body that made Munguia move away.

Munguia caught Resendiz with a right hand that knocked him off balance in the middle minute of the fifth round. That didn’t prevent Resendiz from pressing the action for the rest of the fifth, albeit somewhat ineffectively.

Resendiz and Munguia traded on the inside during the second half of the fourth round. Both boxers landed hard punches during that stretch, though neither fighter appeared hurt at any point.

Munguia landed lefts to Resendiz’s body toward the end of what was a competitive third round.

Munguia got the better of an entertaining exchange that began with about a minute on the clock in the second round. His right hand backed up Resendiz during that sequence, though Resendiz returned to his front foot and snapped Munguia’s head back with a stiff jab about 30 seconds later.