NFL PLAYOFFS : And Now, the Game You’ve Waited for All Season Long : NFC: There is far more at stake than simply a berth in the big show when the 49ers and Cowboys clash today at Candlestick Park. For many of them, this <i> is</i> the big show.

Early this afternoon, around a muddy field on a wind-whipped bay, two teams and 69,500 witnesses will gather for a collision they have seen coming for miles.

A late-scheduled fight marked on calendars for months.

A matchup that has been reality for a week . . . but anticipated for a year.

It is the San Francisco 49ers against the Dallas Cowboys in an NFC championship game that begs a question.

Why did anyone else in the NFL even bother to show up this season?

Why Montana, Moon or Marino? Why the Packers, Lions or Vikings?

Why, even, the Pittsburgh Steelers and San Diego Chargers?

Those latter two will huff and puff about how today’s AFC championship game also has meaning. Then, in two weeks, the winner from there probably will be blown away in the Super Bowl by the winner from here.

For the third consecutive year, the Cowboys and 49ers are meeting in January to determine the best team in football.

Of 235 games scheduled by the league this season, this is the one that truly matters.

Again.

“Why did we even play through the season?” Cowboy receiver Michael Irvin said. “The only reason was to see if we were going to play in San Francisco or here.”

And what a reunion it will be.

Never before in this series has there been so much at stake. Never before has the fear of failure been so palpable.

The 49ers, having lost the last two championship games to the Cowboys, nudged their future out on a limb last spring by acquiring five high-priced veteran starters, four on defense.

If they lose, they fall far and hard. Veterans may leave, a coaching staff may split, the entire organization shaken at its trunk.

“This is truly the reason I came to the 49ers . . . because of this game,” cornerback Deion Sanders said. “This is truly the Super Bowl. I feel like the winner of this game will win the Super Bowl. This is the biggest game of my career. That includes baseball.”

But wasn’t he in a World Series with the Atlanta Braves? And this game isn’t really a Super Bowl.

“Playing in World Series, you get about five chances,” Sanders said. “This game Sunday is one day, all or nothing.”

Steve Young, 49er quarterback and lawyer, for once did not mince words.

“You have to be crazy to think it isn’t imperative that we win the championship,” he said.

The Cowboys, attempting to become the first team to win three consecutive Super Bowl championships, have found themselves on a similar limb.

Owner Jerry Jones fired Jimmy Johnson last spring because of a personality conflict. He replaced him with Barry Switzer, a pleasant man who had never before stood on an NFL sideline.

Talk about falling far and hard.

If the Cowboys lose, Jones will be ripped as just another businessman who doesn’t know squat about football. Can’t do it without Jimmy, they will say.

Switzer may wonder if the hassles are worth it. The team could become divided again between Johnson and Switzer loyalists.

As if things aren’t interesting enough, Johnson, a member of the Fox-TV pregame studio show, will be attending his first Cowboy game since he coached them.

“It doesn’t get any better than this,” Cowboy quarterback Troy Aikman said.

The thing that could throw a wrench into all scenarios is Emmitt Smith’s left hamstring.

Smith, who aggravated an earlier strain last week against the Green Bay Packers, will start today on a Candlestick Park field deluged by recent rains.

But that is the only thing that anybody can guarantee.

“Will he play 60 minutes? I don’t know. Nobody knows,” Switzer said.

Like most Cowboys, Irvin doesn’t think so.

Irvin urged fans (and 49ers?) to take no comfort from the fact that Smith played with a separated shoulder in the final week of last season and throughout the playoffs.

“There are injuries and there are hurts,” Irvin said. “Emmitt has an injury. Last year, his shoulder was a hurt. A shoulder you can grind through. A hamstring is a lot different.”

The Cowboys have lost six consecutive games in which Smith has carried the ball six times or fewer, dating from his rookie season in 1990.

Which means if he is not at full strength, the Cowboys have their excuse and the 49er victory may carry an asterisk.

Not that the 49ers would agree.

“We expect Emmitt to play, and play well,” Young said.

About the matchup and surrounding circumstances, he smiled and added, “Fans and players can’t ask for any more.”

Certainly Young can’t. For the first time this season, the league’s most valuable player is not being asked to beat the Cowboys by himself.

The new 49er defense, ranked eighth in the NFL and second against the run, was one reason Young was able to pass for only 183 yards Nov. 13 against Dallas and still engineer a 21-14 victory.

That defense picked off three passes from Aikman, including two around the end zone, while holding Smith to 78 yards rushing.

It was that victory that eventually brought this title game to Candlestick, where the 49ers are 30-6 in the last four years.

To stop the 49ers’ second-ranked offense in return, the Cowboys must prove that they can stop Young’s bootlegs--he ran for 60 yards in their first game this year--and rush the passer on a wet field.

“With our quickness, a wet field will hurt us a little bit,” Aikman said.

Even if Smith doesn’t play much, the 49ers must also prove they can stop the league’s best postseason quarterback. Aikman is 7-0 as a postseason starter and just waiting to find Alvin Harper, who has averaged 27.9 yards per catch in the playoffs.

Eric Davis, the 49ers’ 5-foot-11 cornerback, has been beaten often in these big games by Harper, who is four inches taller and several steps faster. Judging by the way Davis fled from the media last week, he is well aware of the criticism.

Apparently having exhausted all other avenues, 49er Coach George Seifert has prepared his team for Harper by reminding them of insults.

“I remember one point last year,” Seifert related, “Harper caught a ball then turned to our bench and said something like, ‘What the hell is wrong with you guys? Can’t you cover me?”

The 49ers seemed much looser than the Cowboys during Friday’s news conference, even telling jokes at the podium. Today on the field, though, they must support their claims that this new roster can work well together under pressure.

The Cowboys feel their biggest advantage is that they possess those same close-knit feelings. Only, they say, their feelings are real.

“I just know that when I throw a crack block for Emmitt, I’m not just blocking for a running back, but for a longtime special friend. . . . The same goes with catching passes from Troy,” Irvin said. “It took us years to get like that. Can you build those sort of relationships in a few months?

“You ask me if the 49ers have this. I don’t know. It sounds good when they say it, but I don’t know if it’s true.”

After listening to the Cowboys work their mouths like that all week, Sanders tried to shame them into shutting up.

“To me, when you talk a lot, you are covering up for something,” Sanders said. “I don’t know if that is fear, or if that is trying to talk yourself into doing something you can’t do. I don’t know what it is.”

As they say in Dallas, he is fixin’ to find out. Both teams are. About everything. Themselves, their future, their failures.

As early as last spring, the entire football world knew that one of these teams would be kicking off to the other today at 1 p.m.

The beauty of it is that, even after three years, nobody has even the faintest idea what will happen next.