The difference was the poise of quarterback Joe Montana. During a four-minute stretch, with his San Francisco 49er teammates tired and struggling, Montana's pressure passing today denied the stunned Dallas Cowboys a record sixth Super Bowl appearance.

With the Candlestick Park crowd of 60,525 screaming nonstop, Montana moved his team 89 yards in those four minutes. He completed four passes, the last a six-yarder with 51 seconds left to a leaping Dwight Clark in the back of the end zone. Then Ray Wersching kicked the extra point for a 28-27 victory and San Francisco's first National Football Conference championship.

"We tried to methodically cut them apart," said San Francisco Coach Bill Walsh about that last drive.

And that is what Montana did, executing Walsh's play calls to perfection for a glorious finish to what had been his most frustrating performance of the year. He already had thrown a season-high three interceptions, accounting for half of the 49ers' season-high turnovers, and had been noticeably ineffective against the Cowboys in the second half.

But even after Clark's touchdown, even after their Super Bowl hopes seemed shattered, the Cowboys almost came back. Quarterback Danny White's 27-yard completion to Drew Pearson at the San Francisco 46 had Dallas within 15 yards of Rafael Septien's field goal range. But White fumbled when sacked by Lawrence Pillers on the next play, defensive end Jim Stuckey recovered and San Francisco could begin its celebration.

The 49ers were 2-14 only two years ago, Walsh's first as their coach. Now they have the best record in the league, after removing any doubts that their unexpected performance this year was a fluke.

They had beaten Dallas, 45-14, in October. But that was a flat Cowboy team. This one was not. The Cowboys' front four harassed Montana, forcing him to perform like an inexperienced third-year player instead of the quarterback who led the NFC in passing this season. And their offense was efficient enough to take advantage of his mistakes and take a 27-21 lead with 10:41 left in the game.

Montana's third interception moments later appeared to end the 49ers' chances. Dallas then ran off five minutes, but a poorly thrown third-down pass by White forced a punt to the San Francisco 11.

On the previous three 49er possessions, Dallas had forced turnovers: two Montana interceptions and a fumble by Walt Easley that led to the go-ahead touchdown, a 21-yard pass to tight end Doug Cosbie.

And on the first pass of this latest series, halfback Lenvil Elliott was wide open, but dropped the pass. San Francisco players were dragging back to the huddle and the 49ers appeared on the verge of crumbling before the more experienced Cowboys, making their 15th playoff appearance in 16 years.

But Walsh didn't give up. He crossed up Dallas by calling on his running game, which had been shut down. He sent Elliott around end for six yards. Then he ordered a high-percentage Montana pass that resulted in a six-yard completion to Freddie Solomon and a first down at the 23 that seemed to bring new life to his team.

"We were a little worried that last drive," tackle Keith Fahnhorst said. "But we knew that Joe can take care of himself. He just makes things happen. That drive will go down in history."

Dallas was looking for more passes, but instead two sweeps by Elliott, who had just been activated two weeks ago off the injured list, accounted for 27 additional yards. A five-yard completion by Montana and a Solomon reverse for 14 had the ball at the Dallas 35 with two minutes left.

"We weren't concentrating on anything different," Montana maintained. "We were just confident we could score. In situations like that, I don't fear them. I don't welcome them either, but if it's there, I'll take it."

Suddenly, it seemed Montana could do no wrong, no matter what Dallas tried. And he was receiving wonderful protection after being sacked three times earlier.

He found Clark for a nifty 10-yard completion between two defenders. Then he shredded more double coverage for a 12-yard gain to Solomon and a first down at the 13. Seventy-five seconds remained.

After a timeout, Solomon broke open in the end zone but Montana overthrew him. On second down, Elliott, who had seven carries all season, broke off left end for seven yards to the six. Fifty-nine seconds to go.

Another timeout. Walsh, considered one of the finest offensive tactitians in football, called a play--sprint right option--that Clark said the team "had been having trouble running ever since training camp. We just couldn't get our timing right."

Even now, the timing wasn't correct. Solomon and Clark, lining up on the right side, criss-crossed, with Solomon cutting to the outside. However, the Dallas defense closed on Solomon. Montana, rolling to his right, saw he was covered and didn't throw.

Defensive end Ed (Too Tall) Jones was closing in on Montana as he looked for Clark, who had hooked to the middle of the end zone, then cut back to the deep outside corner with cornerback Everson Walls in pursuit. Montana started to throw the ball away and Jones leaped. Montana repumped as Jones landed, then sent a high pass toward Clark.

Clark, a 10th-round draft choice who caught 85 passes this year and had a 20-yard scoring pass earlier in this game, leaped and stretched his 6-foot-3 frame as high as he could. He held onto the pass and came down just inside the end line. Jones, kneeling on the ground near Montana, shook his head in disbelief.

"When I released the ball, I knew it was high, but I was pretty certain Dwight could get it," said Montana, who finished with 22-of-35 passing for 286 yards, 103 more yards than White. "It wasn't until I saw the replay (after the game) that I noticed it was much higher than I had thought."

Said Clark: "It was a perfect pass; it was right where it was supposed to be."

In the locker room, the 49ers were in ecstasy. "It's unbelievable, unbelievable," said veteran Randy Cross. Linebacker Craig Puki said he still was in shock. "We proved our worth as a team today," he said.

This was the kind of game Dallas usually doesn't lose. The 49ers led the league in fewest turnovers this season, but an aggressive Cowboy defense kept forcing mistakes, kept forcing Montana to throw deep passes instead of his usual short timing patterns.

But despite 91 rushing yards by Tony Dorsett, who came back from a first-half eye injury, the Cowboys never could put away San Francisco, mainly because of three turnovers of their own. Instead, there were seven lead changes.

"The 49ers aren't a better team than us, but the game ended at the right time for them," claimed Dallas Coach Tom Landry, who added: "Montana had to be the key. There's nothing else except him."

Walsh agreed. He talked again and again about his quarterback, who was given the starting job this season when former starter Steve DeBerg was traded to Denver. Walsh has called Montana the best quarterback in the league. Today, the coach said something else about him.

"We were able to win," Walsh said simply, "because we have a resourceful quarterback."