Before they packed their bags and headed to Fresno for Christmas, the New York Giants were asked about Mission Impossible II, beating San Francisco.

"The 49ers are the best team in football right now," linebacker Lawrence Taylor told a knot of reporters around his locker. "That will be our Super Bowl."

The Giants, the NFL's schizophrenic playoff participant, are a team of modest goals.

On Sunday, they played their "NFC championship" in the wild card game, upsetting the Los Angeles Rams, 16-13, to advance to Saturday's NFC semifinal against the 49ers (15-1) at 4 p.m.

For Coach Bill Parcells, who in his second year turned a 3-12-1 team into the most improbable of Super Bowl contenders with a 9-7 regular-season record, it was a day to celebrate. "I feel like all those Christmas mornings put together," he said. "I feel like I'm 23 again."

It's a good thing Christmas came early for the Giants because it isn't going to come when it's supposed to. The Giants aren't going home for the holidays; they are spending the week practicing at Fresno State to avoid the bright lights of the Big Apple.

"I don't know anything about Fresno," said linebacker Harry Carson. "Is that the name of a soda?"

The thread that seems to tie together the latest chapter of the Giants' incredible journey through 1984 is, simply, coming back. This team thrives on being naughty and nice, sometimes within a week.

The Giants lost to the Rams, 33-12, in Week 5 of the season. The following week, they lost to the 49ers, 31-10.

"That was our low point of the season," said running back Rob Carpenter. The Giants had a 3-1 record going into that two-game stretch.

"The Rams physically beat us and intimidated us," Carpenter said, "and San Francisco took us to school. The way this team is playing, we fixed what we did against Los Angeles and beat them, and now we're going to try to do it against San Francisco, too."

What worked on the Rams, who finished five games behind the 49ers in the NFC West, very likely will not work against San Francisco, the first NFL team ever to win 15 games in a regular season.

Carpenter admitted as much. The Giants' game plan against the Rams was designed not so much to win, but to neutralize.

The Giants, utilizing "short stuff," in the words of quarterback Phil Simms, could gain only 192 yards on 62 offensive plays. The Rams gained 214 on 43.

But the Giants didn't make a turnover and were called for only five penalties, although one was a 45-yard pass interference call on free safety Terry Kinard that set up the Rams' only touchdown.

The Rams reciprocated with one of their worst efforts of the year.

"If they had a lot of firepower, like San Francisco, we would have had problems," Carpenter said.

Simms also said the 49ers "are a lot different than the Rams. They are more aggressive physically and faster, which is very good and very bad for the other team. It means you can make plays on them, but they can make them on you, too."

Undoubtedly, the Giants' 10-3 loss to the New Orleans Saints in the final regular-season game sticks out in most fans' minds, but the Giants began the season 2-0, and did have their moments.

"Look at who we beat," defensive end Curtis McGriff said. "We beat St. Louis, we beat Washington and we beat Dallas twice. Okay, we threw away a couple games we should have won, but . . . "

Focus on the last sentence. The New Orleans game didn't mean anything for the playoffs, so the Giants played as if it didn't.

"When we're afraid, we play better," Kinard said. "The first San Francisco game, we got down 21-0 so early and couldn't come back. That will be a different game, just like this one was."

Give credit for the New Orleans-L.A. turnaround to "a little psychology," according to Carson, the team's defensive captain.

Instead of looking at films of the Saints game, or the 31-21 loss to St. Louis the week before that, the Giants pulled out the Washington and Atlanta reels. They beat the Redskins, 37-13, the second time the teams played, and the Falcons, 19-7.

"We looked at films of games in which we played well," Carson said. "We concentrated on the good things we had done. We were getting our minds right."

The Giants, who will need to continue to adapt their offensive game plans to their opponent to go any farther, clearly have crashed the party. So often, teams speak of having nothing to lose and everything to gain. The National Football League's '84 entry in this category wears Giants blue.

"The 49ers are the ones who are worried, not us," Carpenter said. "They've got everything to lose. They're the ones who've got everything on the line, not us. This is our bowl game, now that we're staying out here.

"(San Francisco Coach) Bill Walsh will have headaches staying up late thinking about us."