Joe Theismann bounced down a hallway at Redskin Park and settled in to eat his noontime, brown-bag lunch. But he really didn't need the food. He already was being fueled by adrenaline.

Dallas Week adrenaline.

"No doubt about it, if you were writing a script and I was an actor," said Theismann, "you couldn't write a part for me any better than what's happening now. Any athlete worth his job wants to get into this situation. I love it."

The Redskins are one victory away from their second--and Theismann's first--trip to the Super Bowl. Theismann is nearing the end of what has been by far his most satisfying and most impressive professional season. The only blemish on the season has been a Dec. 5 loss to those Cowboys.

Cut through all the pregame analysis and it comes down to this: if the Redskins are going to beat Dallas Saturday for the NFC title, Theismann must play better than he did 47 days ago. He knows it, his teammates and coaches know it, Dallas knows it.

"I wasn't consistent on my reads that day and I wasn't consistent throwing the ball until late in the third period and in the fourth period," said Theismann, who was sacked seven times. "I've got no explanation for it . . . I just know I can't have three interceptions again.

"But I feel very comfortable and confident now. The defense is playing super and we're running the ball. I realize fully that I don't have to do everything. I just have to do my part just like everyone else has to. If that happens, we'll let the chips fall and see what happens."

Theismann is a man relaxed in the midst of tension, a 33-year-old quarterback who finally has matured into the star he always has wanted to be.

He's a man who has emerged from the first two playoff games of his nine-year NFL career with a pass-completion percentage of almost 74 percent and five touchdowns. He had one interception in the two games. Facing the most important game of his football life, he's on a hot streak.

"He's playing relaxed and with a great deal of confidence," said Joe Bugel, the Redskins' offensive line coach. "He's reached the pinnacle and he doesn't have to prove anything to anyone anymore. Ever since he made the Pro Bowl team, he's even changed some more. He's putting on quite a show."

Some things about Theismann will never change.

He remains frank and wonderfully garrulous, an outgoing, bubbly man who admits to a well-developed ego and a tendency toward self-promotion. But no player is more accessible, more involved in the community and more vulnerable to criticism. And no player enjoys the excitement and very nature of his profession more than he does.

But a lot about Theismann has changed, particularly as a player.

There was a time, not so many years ago, when people within the Redskins organization looked at his interceptions and long, wild passes and wondered if he could ever be a winner.

"If you brought together all the people who didn't think I could be in a game like this, the line would have started to my right and stretched pretty far," said Theismann. "But they should have realized, as I do now, that the fate of a team is not determined by one guy or one position."

In his early days as a starter, Theismann wanted to make things happen so badly he sometimes made bad situations worse. He would force passes into double coverage and go for bombs when flares were more in order. And, oh, would he talk.

"Some people are more vocal about believing in themselves than others," he said. "I prefer to show what I can do by performing . . . But in the beginning when you want to get a chance, you set up a stage. You say I can do this or I can do that, and what you really are doing is, you are defying them to say, 'Okay, loudmouth, go out there and I hope you fall flat on your rear end' . . . I said some things that were foolish just to get the chance to prove that I wasn't really that way.

"It's not really a very sound theory. Trust me, I know. Especially if no one listens to you. You're walking around saying you can do this or do that and they still are playing the other guy . . . The way you're ultimately judged is by performance. That's all I wanted. I wanted a chance."

Theismann still is refreshingly cocky, but he now has the clippings to back him up: starting NFC Pro Bowl quarterback, No. 1-ranked regular-season NFC quarterback, quarterback of the team with the best current record in the NFL, all for the first time.

He's achieved his goals in a most unexpected way. He hasn't been the leading man every week. First, Mark Moseley and now John Riggins have grabbed a large portion of the spotlight, with Theismann in a highly effective supporting role.

"Funny, when Joe Gibbs was hired, I had dreams of what would happen, but not like it's turned out," he said. "I saw myself throwing 40 passes a game and having 10 or 12 300-yard games and throwing 40 touchdown passes . . . We tried that way and it didn't work out and Joe adapted his offense and now everyone feels comfortable with what we are doing.

"When he came here (last season), he didn't know me from squat. We had to get to know each other. He put things in the offense to help me, like more movement where I can sprint out left or right . . . I started off with the ABCs of his offense. I went on to words and sentences and paragraphs. Now I'm into books."

In Gibbs' passing system, Theismann carries an enormous responsibility to be able to read defenses instantly and change on the move. The player who some believed wasn't smart enough now has become a thinking man's quarterback.

"He's intelligent," said Dan Henning, the Redskins' assistant head coach. "He takes great care of himself. And he's always very well-prepared. He's as close as a player can come to being an assistant coach, that's how involved he is . . .It's important to him to know things thoroughly or it bothers him.

"He and we were overextending him at first last year. That's changed. He understands his role and how important it is not to make turnovers and to be consistent . . . Joe has a tremendous work ethic. . . And he won't accept failure. It's a good thing the good Lord gave him talent, because otherwise he would have been very upset. And he might have tried to ask why he was left out."

Theismann: "The most important part of my development has been mental. I have to try to do things mentally where other, bigger guys can get by on physical ability. I know now what it takes for us to win, things like throwing it away when I have to, or protecting a lead or running if I have to or taking a sack.

" . . . I always felt I had to make things happen. Now, if I let things develop, good things will happen. I don't have to look for big plays; they're built into every play, and it's up to me to take them if they are open."

Theismann, a career 55 percent passer, has thrown only one interception in the last 4 1/2 games and only 10 all season. He has had the second- and third-most accurate passing days of his career the past two weeks, in the playoffs. Since the Dallas game, he has been successful on 67 percent of 154 attempts, and has 10 touchdowns among his 104 completions.

But even those statistics still don't completely reflect Theismann's role. "The thing about Joe that impresses me is his heart," said receiver Charlie Brown. "You see that he never quits. So you can't quit, either. He breathes fire."

Theismann: "I've always thought, 'Damn it, if you're going to do something, strive to be the best or go to something else.' I made up my mind last year to become consistent and then what happens, happens. I never doubted that I had set the stage too high for myself, and I never said 'uncle', either.

"But things are only partially completed. The most important thing now is to win Saturday and get to the Super Bowl. Nothing is more important to me than that. Nothing."