Rodriguez, 25, a 2001 national Golden Gloves champion, died Sunday at Hahnemann University Hospital, the first boxing fatality in Philadelphia in 31 years. He had been brought there Friday night after collapsing following a super-bantamweight title fight, won by unbeaten Philadelphian Teon Kennedy.

Surgery was performed to relieve the pressure caused by bleeding in the brain, according to Chicago fight promoter Dominic Pesoli.

"He had no brain functions at all when [his family] decided to remove him from life support," said Pesoli, who had worked with Rodriguez in the past.

The Kennedy-Rodriguez bout, the featured attraction on a six-bout Blue Horizon card, was so spirited that one writer in attendance called it a "once-in-a-lifetime" fight.

While the executive director of the State Athletic Commission said it was unclear whether Pennsylvania's boxing regulations required an autopsy after a fighter died, the city's Medical Examiner's Office said the procedure was routine when death was related to a victim's occupation.

Doug Smith, a neurosurgery professor at the University of Pennsylvania who heads that school's Center for Brain Injury and Repair, said that bleeding caused by a head blow often halts the normal flow of blood to the brain.

"It's ironic that blood stops the blood," Smith said. "The brain is like a sponge that you can only squash so far."

While there have long been worries about the cumulative effect of too many blows to the head in the sport - a concern that more recently has spread to football - it is possible, Smith said, that the fatal injury to Rodriguez was the result of just one punch.

"It could be caused by a single injury, which is what happened to Natasha Richardson," the British actress who died after what appeared to be a minor skiing mishap, he said. "We call it the Talk-and-Die Syndrome. Someone will take a blow to the head, appear to recover, say something, and then lose consciousness for good."

This latest death is bound to provoke critics of the sport, especially coming amid the media spotlight's focus on NFL head injuries.

According to the Journal of Combative Sports, more than 450 fighters have been killed in the ring during the last half-century, most from "brain bleeds."

A study by the American Association of Neurological Surgeons found that 90 percent of the boxers they surveyed had suffered serious head injury.

Friday night's fight, to fill a vacancy in the U.S. Boxing Association's super-bantamweight title, was, by all accounts, particularly physical, filled with knockdowns and head blows.

The fight's promoter, J. Russell Peltz, did not return phone calls yesterday.

Rodriguez apparently took some early punishment from Kennedy (14-0-1) but rallied before succumbing to flurries by his opponent in the ninth and 10th rounds. Referee Benjy Estevez Jr. ended the fight 1 minute, 52 seconds into the 10th.

This is how boxing writer Tim Donaldson described the conclusion of the scheduled 12-round fight in his story, which appeared on the boxing Web site Pound4Pound.

"In the ninth round . . . Teon was battering Rodriguez around the ring. . . . Although Rodriguez looked as though he could go down at any time, he survived to the end of the round. However, Rodriguez could not keep fighting like that. He came back in the beginning of the 10th trying to take control of the round. Teon knocked him down once. Rodriguez survived the count. Teon knocked him down again. He survived the count a second time, but he was shaky. Teon didn't let up the pressure at this point until the referee stepped in and stopped the fight."

Rodriguez (14-3-1) was treated immediately by a physician, Jonathan Levyn, at ringside and, according to Greg Sirb, the executive director of the State Athletic Commission, an ambulance was on standby. Both the physician and ambulance are required by state law.

Levyn could not be reached for comment.

Sirb also said Rodriguez, like all fighters in Pennsylvania, was covered by a $10,000 insurance policy.

The first fighter to die in Pennsylvania was Gil Freeland. In the 169th round of an 1843 bout in Goosetown, Pa., he tumbled to the canvas after a body blow by Philadelphia bricklayer Matt Rusk and never got up.

The previous to die in Philadelphia was Trenton's Jody White after a March 1978 bout with Curtis Parker, also at the Blue Horizon.

In April, another super-bantamweight, Benjamin Flores, died five days after a TKO loss to Al Seeger in Dallas.