Stephan Johnson was on a respirator and in critical condition after he was knocked out in the 10th round by USBA junior middleweight champion Paul Vaden tonight.

Rick Semper, a ringside physician who was briefed by doctors at the Atlantic City Medical Center, said doctors believe there is blood collected between Johnson's brain and skull.

"It is compressing the brain so they are evaluating what they are going to do," Semper said. "This is a major injury. This is the worst kind of thing that can happen to a boxer. On the other hand, they could take it out and he could be fine."

Johnson was expected to undergo surgery early Sunday morning. Trainer Kenneth Woods said doctors want to insert a tube in Johnson's brain to relieve some of the pressure.

"A nurse came out and said they're just trying to keep him alive," said Willie Ross, the fiance of Johnson's mother, who was at the hospital with the fighter.

Johnson and Vaden were exchanging punches in the middle of the ring when Vaden landed a stiff jab and Johnson staggered backward and down. Johnson was taken from the ring on a stretcher.

Woods said Johnson had a similar reaction after a fight in April against Fitzroy Vanderpool. The fighter was taken to a hospital and released after several hours. He was given a clean bill of health and won two fights since then, Woods said.

The scheduled 12-round fight was on the undercard of the Michael Grant-Andrew Golota heavyweight bout in an arena at the Trump Taj Mahal. Grant, seemingly headed for defeat after being knocked down twice by Golota in the first round, pulled out a 10th-round victory.