Only two sure-shot methods of beating the San Francisco 49ers' pass defense have been discovered this season, neither of which really has a whit to do with a chalkboard X or O.

The first:

Let the 49ers take a 27-0 second-quarter lead, then slip a slew of passing Mickeys into their prevent zone while they slumber in a sense of security in the second half.

The second:

Let the 49ers snack at the hotel bar the day before the game and hope their defensive players incur food poisoning.

The Washington Redskins tried the first method. Down by 27-0 late in the second quarter, the Redskins started their passing engines. But even though Joe Theismann threw for 255 yards and two touchdowns in 27 second-half passes, the 49ers still prevailed, 37-31, in Week 2.

"We became much too relaxed in the second half of that game," says cornerback Ronnie Lott. "The Redskins kept getting the ball to (wide receiver) Art Monk and kept spreading out our zone. We can't do that."

The Houston Oilers became the unknowing beneficiaries of the second method: food poisoning, stolen perhaps from a Shakespearean playbook.

Safety Carlton Williamson explains, "Some of our guys ate in the hotel bar in Houston the night before the game. We think (food poisoning) may have been caused by some beers, or something. Or maybe it was some shrimp. Or oysters, I think. Some seafood. We're not really sure."

What the 49ers are sure of is that the Oilers passed for 350 yards, the most against San Francisco this season. Still, the 49ers won, 34-21, in Week 8.

And 49ers defensive end Dwaine Board said two lessons were learned from that experience: "(Oilers quarterback) Warren Moon can really roll out of the pocket and throw on the run" and "I'll never eat in the hotel bar again."

You've heard the trumpets blow all season and all Super Bowl week long for Miami quarterback Dan Marino. But give this San Francisco defense, coordinated by assistant coach George Seifert, more than the shake of a tambourine, too.

This is the defense that yielded the fewest points in the entire league (227, 14.2 per game). It's the defense that began the season by losing cornerbacks Eric Wright and Lott to injury on the first two plays of the opener -- a 30-27 victory over Detroit -- and the defense that has been a resourceful, confident bunch ever since.

This is the defense that used a 3-3-5 defense throughout a 14-5 victory over Atlanta early in the season and held the Falcons without a touchdown even though Atlanta reached first and 10 inside the San Francisco 20 on five drives.

This is the defense that shut out the Los Angeles Rams, 33-0, in Week 9, holding running back Eric Dickerson to 38 yards on 13 carries.

And in beating the Rams by 19-16 in the regular-season finale, the 49ers held Dickerson (98 yards) to only six yards on three carries in the second half.

It's also the defense that recorded eight sacks in a 35-3 victory over New Orleans, the defense that beat down New York Giants quarterback Phil Simms, sacking him six times, intercepting him twice in a 31-10 playoff victory.

And this is the defense that, most recently, recorded nine sacks in a 23-0 shutout of the Chicago Bears in the conference title game.

They can stop the run and deflate the pass, rating near the top of the league in both statistical categories.

In short, this defense can play.

"Our defensive unit this year is more experienced and has more depth," Coach Bill Walsh said, when asked for a comparison with the group that led the 49ers to a 26-21 victory over Cincinnati in Super Bowl XVI. "Unfortunately for us, though, (Miami's) offense is much more potent than Cincinnati's was."

This defense, made tough to decipher by mass substitutions, can be broken down into three integral parts.

First, it possesses a secondary of four Pro Bowl players with a Don't Mess With Me aura: cornerbacks Lott and Wright and safeties Williamson and Dwight Hicks.

Injuries to Lott and Hicks caused the two to flip-flop positions late in the season, Hicks to cornerback, Lott to safety. Another injury forced the pair back to the norm.

"There have only been a few ball games this year where all four of us have played together, without injuries," Williamson said.

Although Lott is listed as the starting left cornerback Sunday, many feel that he will play free safety and Hicks, who has superior speed, will line up at cornerback to defend either of Miami's speedy receivers, Mark Clayton or Mark Duper.

Second, the San Francisco defense possesses a band of veterans who, if not over the hill, are at least somewhere on the downside of the summit.

This group includes middle linebacker Jack Reynolds, 37, and linemen Louis Kelcher, 31, and Gary (Big Hands) Johnson, 31. Both Kelcher and Johnson came north from San Diego this season.

"Coming here has brought us back to life," said Johnson, who recorded 5 1/2 of the team's 51 quarterback sacks. The 49ers have nine defensive linemen (most teams keep seven or eight) and use three role players at nose tackle, Manu Tuiasosopo, Kelcher and rookie Michael Carter.

"Yeah, it is very hard on the ego," says defensive end Jim Stuckey, a former 49ers' first-round draft choice who plays infrequently. "I was used to starting and playing all the time. A lot of us were used to playing a lot. But we understand this goes."

The third and final thread to the 49ers' defense is Fred Dean, one of the league's preeminent pass rushers. To some, this unit is called the Deanfense. It's no wonder.

Dean, 32, was a contract holdout through the first 11 weeks of this season. Team owner Eddie DeBartolo Jr. became so enraged at stalled negotiations he threatened to keep Dean tangled in court "until he's 50". To prove his point, DeBartolo sent a rocking chair to Dean's home.

Once signed, however, Dean produced 4 1/2 sacks in the final five regular-season games. Now, the 49ers are ready to give Dean a chair of royal velvet.

"Fred's the best pass rusher in the league, bar none," says Stuckey. "We always kid Fred that we were 10-1 without him, but we all know that for us to ever get to the Super Bowl, we had to have Fred."

Lott says he has seen many offensive tackles peeking out of the team huddle to see if Dean is in the game and on which side he will be positioned.

Dean says he is double-teamed "80 percent of the time.". He knows that Marino, with an adept offensive line and a quick release, has been sacked only 14 times in 18 games.

"You have to wonder about something like that," Dean said, shaking his head in admiration. "But you also have to look at this way. I mean, he has been sacked 14 times."

Dean's eyes grew wide, real wide, Super Bowl-wide. "Right now," he said, "I feel like I'm in the flow. I'm ready."