As Ricky Smith, the Washington Redskins' third-year cornerback, lay on the grass near midfield without moving yesterday, RFK Stadium grew about as quiet as a place filled with 55,000 people can be.

While tackling Dallas fullback Timmy Newsome, Smith suffered what was later diagnosed as a concussion. He was unconscious on the field and was taken to Arlington Hospital, where he was being held overnight for observation.

A CAT-scan and X-rays proved negative, a team spokesman said. Mitchell Heiman, an emergency department physician at the hospital, said Smith was "in good condition. We will admit him probably just for a one-day observation."

"It's just a headache," Smith said.

He said the last thing he remembered was, "I had to jam my receivers and check on anyone coming across the area. A guy came across and I tried to make a good tackle. I went low on him, and I guess his knees hit my head."

"I was out for about 90 seconds," Smith said. "On the field, I could open my eyes, but it wasn't until I was being put on the ambulance that I could understand what was happening."

"Neck and head injuries are so dangerous," Redskins defensive tackle Darryl Grant said. "When the stretcher went out, all you could do was hope for the best, but you just don't know. It was really a down moment.