Boxer Maxim Dadashev was rushed to a hospital late Friday night after he collapsed outside the ring following a loss to Subriel Matias. (Mikey Williams/Top Rank)

Boxer Maxim Dadashev collapsed outside the ring late Friday night following a loss to undefeated Subriel Matias in their 140-pound bout and was transported to a hospital to be evaluated by a head trauma specialist, according to officials from ESPN and Top Rank promotions.

In a chilling series of events minutes after Matias scored a technical knockout when trainer James “Buddy” McGirt stopped the fight before the 12th-round bell, the Russian-born Dadashev collapsed in the aisle at the Theater at MGM National Harbor and was lifted onto a stretcher, at which time he began vomiting.

Emergency medical technicians immediately attended to Dadashev, who initially was being transported to Washington Adventist Hospital in Takoma Park, officials said.

Fight officials later said Dadashev had been responsive in the ambulance on the way to Washington Adventist but then became unconscious, prompting a decision to transport him to University of Maryland Prince George’s Hospital Center.

At around 2:30 a.m. on Saturday, doctors told reporters that Dadashev underwent surgery for swelling on his brain, a procedure that took about two hours. His manager, Egis Klimas, and his strength and conditioning coach, Donatas Janusevicius, were both at the hospital, where he was expected to remain for days.

Dadashev’s wife, who was in Russia, was expected to fly to the United States soon.

“I just think that he took a lot of shots, totally dehydrated,” said McGirt, a former welterweight. “I believe he needs [intravenous fluids]. He took a lot of shots, and every time I gave him water, he kept spitting it out. Those were 11 tough rounds, so I just pray that he’s okay.”

The fight served as the co-feature to the main event matching Teofimo Lopez and Masayoshi Nakatani, both undefeated, in an International Boxing Federation 135-pound world title eliminator. Lopez defeated Nakatani via unanimous 12-round decision, with two judges scoring the fight 118-110 and a third 119-109. The victory secures Lopez a title fight against IBF 135-pound champion Richard Commey.

Dadashev, 28, had not lost in 13 fights entering his bout against his Puerto Rican-born opponent.

Matias (14-0, 14 knockouts) had been administering plenty of punishment during the late rounds, landing repeatedly to the body with combinations. Dadashev labored to land much of anything over the latter part of the fight, instead covering up with Matias stalking him.

“I just hope that Maxim is all right,” said Matias, 27. “He is a great fighter and a warrior.”

After the bell sounded to end Round 11, Dadashev sat on the stool in his corner surrounded by McGirt and cornermen Roger Anderson, Janusevicius and Klimas.

Referee Kenny Chevalier moved in the direction of Dadashev’s corner to check on the status of the fighter for the next round, at which point McGirt informed Chevalier he was going to stop the fight.

“I think he needs more IVs in him,” McGirt said. “I’m not a doctor, but I mean he didn’t want to drink much water. He kept spitting it out. He had one hell of a fight. Tough fight. Took a lot of body shots.”

“I just think it was time to stop it. He was taking too many shots.”

The scene recalled another gruesome aftermath of a local boxing match in October 2015 at EagleBank Arena in Fairfax when super middleweight Prichard Colon began complaining of dizziness after being disqualified in a loss to Terrel Williams.

He eventually collapsed and was examined by ringside physician Richard Ashby. EMTs transported Colon to Fairfax Inova Hospital, where he underwent surgery for bleeding on the left side of his brain.

Colon remained in a coma for nearly seven months, with medical specialists predicting he would spend the rest of his life in a vegetative state.

He eventually regained consciousness and continues extensive rehab in a facility in Orange Park, Fla.

Friday’s undercard concluded with local favorite Dusty Hernandez-Harrison stopping Juan De Angel via a seventh-round technical knockout to keep the District middleweight undefeated.

Although his corner was understandably pleased with the result, the fight didn’t go exactly according to plan, according to Hernandez-Harrison (33-0-1, 19 KOs), who had designs on a knockout much earlier in the bout.

But his opponent proved more resourceful than anticipated, forcing Hernandez-Harrison, 25, to lay back in the early rounds before breaking down De Angel (21-12-1, 19 KOs) with superior power to earn a referee’s stoppage at 2:30 following a right-left combination to the body.

“I thought it took me too long to get in an offensive rhythm,” Hernandez-Harrison said. “He had a very funky little rhythm himself, and he hit hard, so it keeps you honest. You didn’t want to sit there in front of him too long, but eventually I kind of had to take some shots to get my offense going, and it worked.”