Andre Berto probably wishes he remained retired.

The former IBF/WBC welterweight champion came to fight Saturday night, but he lost another unanimous decision to Robert Guerrero in their 10-round rematch on the David Morrell Jr.-Sena Agbeko undercard at The Armory in Minneapolis. Berto had his moments, but judge Mike Fitzgerald scored nine rounds for Guerrero (99-91) and judges Tim Cheatham (98-92) and John Mariano (98-92) scored eight rounds apiece for the southpaw in the opener of the final “Showtime Championship Boxing” broadcast of the network’s 37 years in boxing.

Berto (32-6, 24 KOs) fought for the first time in five years to try to avenge his decision defeat to Guerrero 11 years ago. It amounted to an ugly battle between 40-year-old ex-champions marred by incessant clinching and fouling by both boxers.

Guerrero (38-6-1, 20 KOs, 2 NC) knocked Berto the canvas once apiece in the first and second rounds of their first bout, quickly caused swelling around both of Berto’s eyes and won by the same score, 116-110, on all three scorecards to win the then-vacant WBC interim welterweight title at Citizens Business Bank Arena in Ontario, California. There weren’t any knockdowns Saturday night, just a lot of wrestling and breaks called by referee Robert Hoyle to warn Berto and Guerrero for their rule-bending tactics.

Berto, of Winter Haven, Florida, ended a five-year layoff. He fought for the first time since he defeated Devon Alexander by split decision in their 12-rounder in August 2018 at Nassau Veterans Memorial Coliseum in Uniondale, New York.

Guerrero, of Gilroy, California, ended a two-year layoff. He boxed for the first time since his 10-round, unanimous-decision victory over Victor Ortiz in August 2021 at T-Mobile Arena in Las Vegas.

Fittingly, Hoyle called for a break one last time with 11 seconds to go in their bout because Berto hit Guerrero on the back of his head with a left hand. Despite all of the rule-breaking tactics, Guerrero and Berto showed respect for each other and hugged as soon as the final bell sounded.

A straight left by Guerrero knocked Berto backward with just under 1:10 on the clock in the 10th round.

Berto drilled Guerrero with his right hand a little less than 40 seconds into the ninth round.

A right hook by Guerrero wobbled Berto with about six seconds to go in the eighth round. Berto complained that Guerrero hit him behind his head, but that shot appeared to land on Berto’s jaw.

Hoyle called for time with 36 seconds on the clock in the eighth round because Guerrero hit him low with his left hand.

Hoyle called for time and warned Guerrero for hitting Berto on the back of his head with 1:25 to go in the seventh round. Berto belted with a right hand that knocked Guerrero off balance barely 20 seconds into the seventh round.

Guerrero blasted Berto with his left hand just before the bell sounded to end the sixth round. Berto’s right uppercut caught Guerrero when they were clinched against the ropes earlier in the sixth round.

Guerrero landed a left uppercut a few seconds after connecting with a straight left when there was just under 45 seconds to go in the sixth round.

A left by Guerrero buzzed Berto with just over 1:20 remaining in the fifth round. Berto slipped and slid his way out of that trouble.

Berto went down 45 seconds into the fifth round, but Hoyle ruled that Guerrero pushed him down.

Berto and Guerrero clinched and punched until Hoyle separated them toward the end of the fourth round.

Hoyle implored Berto and Guerrero to fight clean a little less than a minute into the fourth round. A sweeping right hook by Guerrero landed as Berto backed into the ropes about 30 seconds into the fourth round.

Guerrero’s left uppercut caught Berto with approximately 20 seconds to go in the third round. He then hit Berto with a right hook, which caused Berto to tie him up.

Berto awkwardly went between the second and third ropes about 40 seconds into the third round as Guerrero pursued him.

Berto’s right landed as Guerrero tried to back away from him with 15 seconds on the clock in the second round.

Guerrero landed a straight left a little more than a minute into the second round. Berto quickly responded by connecting with a right-left combination that backed up Guerrero a few seconds later.

Berto and Guerrero, both coming off long layoffs, spent most of the first round feeling each other out. Neither fighter landed a consequential punch in those opening three minutes.

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