During one of his numerous visits in the Miami backfield tonight, sometime during the third quarter, San Francisco nose tackle Manu Tuiasosopo thought he heard someone say something. He turned around.

"Who was that?"

Quarterback Dan Marino was talking, and he was exasperated.

Tuiasosopo looked at Marino. "Are you talking to me?"

Marino didn't say anything else, so Tuiasosopo went to his huddle.

"He must have been referring to Fred Dean, who was in on him on that play," Tuiasosopo said after the 49ers defense ruined Marino's first Super Bowl in the 38-16 San Francisco victory.

"It was like Marino had a radar gun back there and had it on Dean and Dwaine (Board) as they came through."

If Marino is the best quarterback in the game, what does that make the 49ers' defense? It did what no other defense was able to do to Marino this year -- pressure him, force him to make mistakes, totally frustrate him.

"He was getting impatient," said free safety Dwight Hicks, one of four San Francisco defensive backs going to the Pro Bowl. "I don't know if he was getting intimidated, but he was frustrated by all the short passes he had to throw."

When Marino wins, he beats you long. He has time. He never loses his composure.

Today, he had none of that, although his statistics (a record 29 of 50 passes for 318 yards) sound good. But the Dolphins scored just one touchdown, which means, basically, the 49ers stopped the unstoppable.

After the victory, one that offensive guard Randy Cross said was "a fantastic victory for our defense," the 49ers could hardly have been less surprised.

"All two weeks leading up to the game, everyone kept asking, 'How are you going to stop him? How are you going to stop him?' " Hicks said.

"Well, no one knew but us."

Now it can be told; disappointingly, it really was no great secret. There were no new defenses or coverages thrown in to stop Marino. There were no gimmicks.

The 49ers simply went to their nickel defense -- five defensive backs and reserve strong safety Jeff Fuller as a swing linebacker/defensive back -- as soon as Miami scored its first (and only) touchdown.

San Francisco rotated defenses throughout the rest of the game, but used the nickel defense much more than any other.

"We conceded the short pass and would not let them get anything longer," said Hicks.

Marino's longest completion of the day was 30 yards to Joe Rose in a drive to a 31-yard field goal by Uwe von Schamann.

"In the first half, we knew holding (Mark) Duper and (Mark) Clayton would be the key," said cornerback Eric Wright. "It would all be determined on what kind of day we (the cornerbacks) had."

Two plays by Wright told the story.

With the 49ers ahead, 21-10, midway through the second quarter, Marino threw what would have been a first-down pass to Duper. The way the lead was changing hands at that point, it was logical to figure the Dolphins were about to score another touchdown.

Wright, playing off Duper a step or two, sneaked up at the last second, stuck out his left hand and swatted the ball away. Miami was forced to punt.

Then, with less than four minutes left in the third quarter, Wright made the catch of the game, an over-the-shoulder interception of Marino's pass at the goal line. San Francisco's 38-16 lead was secure and held up the rest of the game.

There also were four sacks on Marino for losses of 29 yards.

"We didn't sack him a lot, but we sacked him enough," Hicks said.

No one sacked Marino more this season. The Los Angeles Raiders had three, and that was considered some kind of miracle.

"I watched the tape (of that game) a lot," said defensive end Board, who sacked Marino twice.

But the sacks were not as important as the pressure they signified. One of the joys of watching Marino pass is how quickly his head and eyes move as he searches for receivers.

This time, he looked once -- and couldn't look again. He might as well have been wearing blinders.

"He couldn't go back to his primary receiver," said Hicks, gleefully.

The 49ers seemed almost awestruck with themselves. "He had to throw the early pass," said Tuiasosopo. "Sometimes he threw the ball and his receiver had not even turned around yet."

To which Board added, "The Marks Brothers (Duper and Clayton) looked like clowns."

The 49ers allowed the Dolphins to keep the ball only 23 minutes to their 37. The Miami running game went nowhere, with only 25 net yards. The 49ers said they couldn't pay attention to the running game, but it was hard to tell. On several occasions, there was doubt if Marino's handoff was going to a Dolphin or a 49er.

"The only time I was worried was press day," said Board, the most ferocious of all pass rushers tonight. "That was 'How do you stop Marino?' day."

The answer came today.