John Avila, 17, captain of the football team at Stuart High School in Falls Church, was in critical condition last night at Alexandria Hospital with a life-threatening brain injury suffered in his team's football game Friday night at Edison High School in Alexandria.

Avila, who played guard on offense and linebacker on defense Friday night, came out of the game after making a tackle in the third quarter.

Dr. Gerard Engh, an orthopedic surgeon who is Edison's team physician, treated Avila on the sideline. The player was taken by a Fairfax County Fire and Rescue Department ambulance to Alexandria Hospital.

He went into the operating room at 12:30 yesterday morning and underwent 4 1/2 hours of surgery to relieve pressure on his brain, according to a family friend, Manny Fierro, whose son, Manny Fierro Jr., also plays for Stuart.

"He is on a life support system now and it does not look good," said Fierro Sr., acting as a spokesman for the Avila family. "The family will know more in the next 72 hours, but, outside of a miracle, it may not be possible to pull him out of it."

Alexandria Hospital officials listed Avila's condition as critical, but would not elaborate. Neurosurgeon Aldo Rosenblat of Falls Church, who performed the surgery, said he could not comment without the permission of the family. Engh was unavailable.

The injury comes a year after two Virginia football players -- Brandon Dawson of Stonewall Jackson High School in Mount Jackson and Chuck Coles of Potomac High School in Dumfries -- died. Each was stricken on the football field.

Avila, a 5-foot-9, 190-pound senior, told his teammates on the field that he was dizzy and having difficulty seeing in the third quarter, according to a family friend. But he stayed in for another play, made the tackle, then left the field without assistance.

Witnesses said his condition worsened as a team trainer spoke to him on the sideline, and Avila lapsed into unconsciousness several minutes later.

In a brief interview last night, John Avila's father, Moises Avila, said the injury was on the left side of the brain.

He said his son was on a respirator and that "we have 72 hours to see what happens. I am hoping tomorrow we will know more. But he is in bad shape."

David Morgan, athletic director at Stuart High School, said Avila has been in the football program for three years and is one of the best players on the team.

"He's a good student, just a super kid," Morgan said yesterday. "We're just stunned by this. Everyone loves and respects John. It's just the worst possible thing that could happen."

Morgan said Avila previously had no history of being seriously hurt playing football and that "when I went into the locker room at halftime he seemed fine. I talked to him and there didn't seem to be any problem."

He said his coaching staff had reviewed films of the game and described the tackle as "just routine. The game films didn't show any situation out of the ordinary. It wasn't a devastating tackle."

The elder Avila said his son had told him Thursday night that he would be playing both offense and defense. "I told John I did not think it was a good idea," said Moises Avila, a native of Colombia who came to the United States 17 years ago. "But he wanted to do it . . . He loved to play the game.

"I was at the game. It was obvious to me the boy was tired. I told the coach {at the hospital Friday night} this {playing offense and defense} was a mistake."

Stuart Coach Tom Arehart, in his fifth season at the school, could not be reached for comment last night. He and his staff and several players stayed at the hospital until early yesterday morning.

Arehart met with his players at 8 a.m. yesterday to tell them about Avila's injury.

"We're in a state of shock," Morgan said. "Fairfax County has a crisis resource team to help our kids deal with this, and we'll be calling them in on Monday. No one can believe this has happened."

Staff writer Sandra Bailey contributed to this report.