Jaime Munguia’s B-sample returned an adverse finding for exogenous origin of testosterone on Friday, sources tell The Ring..

Munguia now faces discipline from the BBBofC and could see his decision victory over Bruno Surace overturned to a no-contest. The BBBofC’s Robert Smith didn’t immediately respond to a text message seeking comment.

Munguia (45-2, 35 KOs) had 10 days to request analysis of his B-sample for exogenous origin of testosterone and its metabolites (aka synthetic testosterone) after his A-sample tested positive last month.

Mexico’s Munguia, 28, defeated Surace in the super middleweight rematch after he was KO'd in Round 6 by the Frenchman in December in The Ring’s Upset of the Year.

“Now that Munguia’s B-Sample also is positive, I look forward to the BBBofC overturning the result and also taking appropriate action against my opponent,” Surace, 26, told The Ring on Tuesday.

“There’s simply no place in boxing for this conduct. I’m looking forward to again proving my knockout over Munguia was not a fluke. I would love to fight the winner of the Berlanga-Sheeraz fight in July.”

Team Munguia released a statement later Tuesday: "We want to reiterate that this outcome does not change our position: Jaime did not knowingly or intentionally ingest any banned substance. We remain steadfast in the belief that this result was caused by contamination, and we are continuing to take every possible step to identify the source."

Surace (26-1-2, 5 KOs) was a major underdog when he traveled to Tijuana, Mexico, in what amounted to a stay-busy fight for Munguia. After all, Surace was moving up one weight class and had scored just four career KOs.

In a career-defining victory, Surace sprung the upset when he landed a massive right hand in Round 6 that planted Munguia on the canvas for the 10 count.

Munguia linked up with renowned trainer Eddy Reynoso ahead of the rematch and held training camp in the Sierra Nevada mountains alongside former foe Canelo Alvarez. (Alvarez defeated Munguia in May 2024.)

And then on the undercard of Canelo’s victory over William Scull in May, Munguia exacted revenge with a unanimous decision victory over Surace in a competitive fight. Following the fight, Munguia climbed to No. 5 in The Ring’s 168-pound rankings while Surace fell to No. 8.

But now, that victory could be eliminated as Munguia faces discipline following a rocky 2024 where he suffered the first two losses of his career.

“I have spent my entire career and life doing things the right way — and this is no exception," Munguia said via statement. "I love boxing, and I am the first one who wants to clear everything up because boxing is my life. I can’t wait to get back in the ring. We’re going to prove that we never disrespected the sport, my opponents, or misled the fans.”