Four months ago, it would have seemed ludicrous to predict that the San Francisco 49ers and the Dallas Cowboys would be matched up in the National Football Conference championship game.

Dallas, one of the National Football League's elite teams, certainly seemed capable of getting this far. But not San Francisco, a club coming off a 6-10 season with 20 new players, an inexperienced quarterback and three rookies starting in its secondary.

So why, then, are those same 49ers, who boast the best record in the league, so convinced they can beat the mighty Cowboys Sunday (5 p.m. EST, WDVM-TV-9) and advance to the Super Bowl?

"We have every reason to be confident," Coach Bill Walsh said. "We've won 13 of our last 14 games, we're playing at home and we've beaten Dallas before. All that should offset their edge in experience."

But how do you measure the motivation Dallas received from the 45-14 beating San Francisco handed the Cowboys here in October? Dallas rarely loses to the same team twice in one season, and rarely loses when it is properly aroused.

And the Cowboys are properly aroused.

"We weren't that impressed with them even when they beat us," said Ed (Too Tall) Jones, the most vocal Cowboy this week. "We didn't play very well. They caught us on a flat week. But we won't be flat this time."

Dallas, however, may not be at full strength. Guard Herb Scott, an all-pro, has a bad ankle, and defensive tackle John Dutton, coming off a fine season, has a sore thigh. If they can't start, they will be replaced by rookie Glen Titensor and veteran Larry Bethea, and that's a considerable dropoff in talent.

There also is the matter of the slow Candlestick Stadium turf, which may neutralize Dallas' advantage at running back. The 49ers have no one who can compare with Tony Dorsett, but he's never gained 100 yards against San Francisco and he may have problems cutting on the still-heavy, still-loose field.

San Francisco's leading rusher, Ricky Patton, is hobbled by a bad ankle and will be replaced by Lenvil Elliott. But the 49ers' running game is secondary to their passing attack, anyway. Walsh says his team will pass a lot, using this approach to control the clock and, hopefully, the game.

"It will take 28 points, at least, to win it," Walsh said.

"I'd take 28 and sit on it," Dallas Coach Tom Landry said.

In their earlier game, San Franciso led, 21-0, before Dallas had a first down. Cowboy quarterback Danny White was intercepted twice and the Cowboys lost two fumbles. San Francisco had one turnover and quarterback Joe Montana was 19 of 29 for 279 yards.

"Turnovers are very important," Landry said. "San Francisco had the best turnover ratio in the league and we forced the most interceptions. It's difficult to force them into turnovers. They play that well."

Landry hopes to disrupt the 49ers with the rush of his front four, which had only one sack in October. "The key," said Jones, "is getting pressure on Montana." Montana, who relies mostly on quick, short passes, was sacked only 29 times in the regular season.

Dallas couldn't stop end Fred Dean in that earlier game. Dean made his 49er debut after a trade with San Diego by registering three sacks. He'll be matched up on passing downs against all-pro tackle Pat Donovan.

"We're a better team now than we were earlier," Landry said.