Boxer Kiko Bejines, who never regained consciousness after being knocked out by Albert Davila Thursday night, died today of head injuries, officials at Los Angeles County-USC Medical Center said.
Bejines, from Guadalajara, Mexico, was 20, said hospital spokesman Tony Tripi. Tripi said Bejines died of massive cerebral contusions.
An autopsy was to be performed before the body was returned to Mexico for a funeral.
Three neurosurgeons operated on Bejines Friday afternoon, removing part of the boxer's brain and skull and also removing a blood clot on the surface of his swelling brain in an attempt to relieve the pressure.
Bejines had been on a respirator, but his heart was beating on its own until he died, Tripi said.
Bejines' wife, awaiting the birth of the couple's first child, remained in Guadalajara. She was not told of her husband's injury until Friday after the operation.
"What with her pregnant, we didn't want to tell her anything until we knew for sure. Why does this thing have to happen?" Obdulio Munoz, Bejines' manager, said before the fighter died.
Bejines, the eldest of three boxing brothers, suffered the fatal injury in the 12th round of the bout against Davila for the vacant World Boxing Council bantamweight championship.
The bout, in which neither fighter was able to score any telling blows through the first 11 rounds of the scheduled 12-rounder, ended abruptly 33 seconds into the final round when Davila unleashed a flurry of punches to Bejines' head.
Bejines stumbled backward into the lower rope and attempted to regain his feet, but referee Wildemar Schmidt declared the fight over.
In Mexico City, Arturo Hernandez, manager of former WBC bantamweight champion Lupe Pintor, conjectured "apparently, Bejines was hurt beforehand.
"The Mexican's guard was down from the ninth round, while his rival appeared to be in good shape. Bejines had something wrong with him from before the fight," Hernandez said.
Bejines became the third professional fighter to die from boxing injuries suffered in a world championship bout in this decade.