The San Francisco 49ers won today the way they usually win. They pull out of the garage going 80, and then put it on cruise control. That way, it's almost impossible for anyone to catch them.

Ask the New York Giants, who, before Candlestick Park's second largest crowd, 60,303, became the 49ers' 16th victim of the 1984 season. The 49ers scored 14 points in their first 10 plays today and the Giants, try as they might, could never catch up, losing this NFC semifinal game, 21-10.

"They are the same old 49ers," said Giants cornerback Kenny Daniel, echoing the feelings of his teammates. "They get a lead and sit on it."

The 49ers (16-1) will play host to the winner of Sunday's Washington Redskins-Chicago Bears game next weekend at Candlestick Park in the NFC championship game. The winner will go to the Super Bowl.

The Giants, who went farther than most expected after sneaking in the back door of the playoffs, finished 10-8.

For winners, the 49ers sounded rather strange in their locker room. A 14-0 lead in the game's first seven minutes is pretty good; a scoreless second half is not.

"This day showed we are as vulnerable as anybody else," said tight end Russ Francis, who caught the second touchdown pass from quarterback Joe Montana. "I think it's possible we were sort of shocked when we went ahead, 14-0. We said, 'Now what do we do?' "

The answer: Almost nothing. The Giants relied on two interceptions to score 10 points in the second quarter before the 49ers scored one last time right before halftime.

"This shows we're certainly a team people can deal with," said Coach Bill Walsh. "Next week, we can't play that way."

"We were not nearly as sharp as we can be," said San Francisco offensive guard Randy Cross. "There is a lot of room for improvement."

If the game could be capsulized by the play of one person, it would be Montana. He threw three touchdown passes and had 309 passing yards on a 25-for-39 day and scrambled 53 yards once in the third quarter, but he threw three interceptions, one returned 14 yards for a touchdown by linebacker Harry Carson.

"If they don't run the interception back and I throw a little higher on the goal-line interception (in the third quarter), we could have put it away early," Montana said.

In some ways, they did. The start was vintage San Francisco; seven times this season, the 49ers have scored the first time they touched the ball.

With the usual balance of running and passing (and a pass-lateral good for 13 yards on the first play thrown in) the 49ers moved 71 yards in the first three minutes.

On the touchdown play, from the 21-yard line, Montana faked a draw, watched the play unfold with plenty of time, and then threw to Dwight Clark at the goal line.

Clark reached high for the pass over safety Terry Kinard and fell into the end zone for the touchdown.

The 49ers' next touchdown was set up by a pinball interception. From the New York 40, the Giants' Phil Simms tried to throw to Lionel Manuel, but the pass was tipped at the line by linebacker Dan Bunz. It then flew downfield and bounced off linebacker Riki Ellison's shoulder into cornerback Ronnie Lott's hands at the 50.

Lott returned 38 yards to the 12. Roger Craig gained three in the middle before Montana found Francis on a short post pattern for the nine-yard touchdown. Francis was designated the third receiver on the play.

"This was a play we had never run (to the tight end) before," Francis said. "Dwight was double-covered, so I tip-toed into the end zone and Joe was nice enough to throw it over the linebacker's head.

"It was a confusing play. It was confusing to us, too. I was just nodding my head; I guess it worked."

It was beginning to look a lot like the last 49ers-Giants game, in which the 49ers took a 21-0 lead in the first eight minutes and coasted to a 31-10 victory.

Simms, who completed 25 of 44 passes for 218 yards, said the quick start caused problems the rest of the game.

"They got us down, 14-0, and were able to take liberties on defense," he said. "Once we got back into the game they (the San Francisco defenders) had to play it more conservative."

The only true resemblance between games, however, turned out to be the way the 49ers coasted through most of the rest of the game.

They allowed the Giants to get back into the game before driving to their third touchdown late in the first half on a 29-yard reception by Freddie Solomon to increase their lead to 21-10.

After the two touchdowns, the 49ers' four possessions ended in a punt, interception, punt and interception. The first interception went through Clark's hands, bounced off Kinard's hands, and went to linebacker Gary Reasons at the New York 34.

The Giants drove 37 yards in 11 plays before Ali Haji-Sheikh missed a 46-yard kick with 11:34 to play in the half. The next interception was Carson's touchdown.

With 6:41 left, the Giants had pulled within four, but the 49ers came back on a 73-yard, five-play drive, aided by a questionable late-hit call on strong safety Bill Currier.

Solomon gained 16 on a reception to the New York 44. As he was headed out of bounds, Currier dived against him, seemingly unable to stop, and the penalty put the ball at the 29.

On first down, cornerback Perry Williams slipped trying to cover Solomon, and Montana threw a 29-yard touchdown pass.

The Giants squandered a first down at the San Francisco 11 on a sack and two incompletions, followed by Haji-Sheikh's missed 33-yard field goal with 9:43 to play. It was that kind of series that was made possible by the early lead, 49ers defensive tackle Gary Johnson said.

"We probably would have been in our base defense looking for the run if we had not had the lead," he said. "Instead, we could call a lot of defensive stunts and games.

"It was great; we just pin our ears back and go."