ON a Sunday afternoon a few weeks ago, Jeff Fuller was at his mother's home in Dallas with several friends when somebody asked if he minded watching a pro football game on television. ''Who's playing?'' he asked. ''The Patriots,'' he was told. ''Not them,'' he said. Not the Patriots, thank you. On Oct. 22, only moments after the San Francisco 49ers kicked off, Johnny Stephens, the New England Patriots running back, had turned the corner on a sweep when Fuller tackled him near the sideline. One of hundreds of hard tackles every Sunday in pro football. After the collision, Stephens hopped to his feet, but Fuller didn't. Stretched out on his back on the Stanford Stadium grass, the 49er safety appeared unconscious.

''I wasn't unconscious; I just couldn't move,'' he was saying now. ''I remember everything.''

He remembers looking up at all the doctors and trainers as the facemask on his gold-and-scarlet 49er helmet was unscrewed so he could breathe easier. He remembers being lifted onto a gurney that rolled him to an ambulance. He remembers the ride to nearby Stanford Hospital where his neck injury was eventually diagnosed as severe damage to the nerves that control his right arm. The right arm he still can't move.

''But I look at it as a miracle,'' he said. ''Because for a few moments I couldn't move at all.''

Of all the injuries in the National Football League this season, Jeff Fuller's has been the most alarming. Bones and ligaments in other players have been surgically repaired, cobwebs in other players' heads have been cleared after concussions. But as the Super Bowl XXIV playoffs approach, Fuller's right arm hangs limply inside his long-sleeved shirt.

''They still don't know if the nerves were stretched, torn or what,'' he said. ''I can't make a fist but I've got a little finger movement and it's starting to hurt. That's a good sign.''