The composite sketch shows he possesses Joe Namath's arm, Sonny Jurgensen's belly, Johnny Unitas' Pittsburgh swagger and Dan Fouts' lead feet and iron will inside the passing pocket.

And now comes the moment for Dan Marino, Miami's 23-year-old quarterback, to be nothing more than himself, and he has been nothing short of remarkable all 55-touchdown-pass season.

So clear the stage for Super Bowl XIX between the Miami Dolphins (16-2) and the San Francisco 49ers (17-1) because, beginning at 6:17 p.m. EST Sunday (WJLA-TV-7) at Stanford Stadium, this surely will be Marino's show.

The question is, will Marino be able to deploy his three-step drop and quick-flick release to make this his own Super Bowl?

To connect with his two deep-threat dynamo receivers (Mark Clayton and Mark Duper), Marino must overcome a surly defense that most likely will often deploy five defensive backs with an added fourth lineman, pass-rushing phenom Fred Dean.

"If we don't put pressure on Marino, he'll eat us alive. He'll tear us out of the frame," said defensive lineman Jim Stuckey of the 49ers. "We've got to get the pressure from up the middle, too, because he's not bothered by pressure from the edges."

And 49ers Coach Bill Walsh said of Marino, "Everything points to him breaking every conceivable record set by a forward passer . . . He's the greatest passer of all time, as I understand it."

Of course, there are reasons the 49ers are three-point favorites, reasons that extend far beyond the fact that the 49ers will have a home town crowd. After all, the Los Angeles Rams had the home town advantage in Super Bowl XIV, but lost to Pittsbugh, 31-19, in a game played in the Rose Bowl in Pasadena.

"In this contest," Walsh said, "the magnitude of the game overwhelms the factor of whether you're playing home or away."

The 49ers' quarterback is Joe Montana. They may call Marino the Second Coming of Joe Namath, but they simply call Montana "Joe Cool." It is Montana's resourcefulness, his dink-dink-Bomb!-dink modus operandi, his ability to scramble for first downs and the way he locates receivers such as Dwight Clark and Freddie Solomon even when pressured that opens the door for potential gold strikes by the 49ers Sunday.

And if running back Wendell Tyler, a Pro Bowl selection who ran for 1,262 yards this season, avoids his propensity of fumbling, he could cause further damage to the Dolphins.

This is what strikes to the very heart of this game: both offenses can produce quickly and often. It's just that Miami's defense has had so many inconsistencies this season. In the only games that Miami lost, the Dolphins scored 34 and 28 points.

Miami rates 22nd in the league in run defense, partly because inside linebackers Jay Brophy (rookie) and Mark Brown (second year) still are learning their craft.

Eight starters remain from Miami's "Killer Bs" defense that the Redskins run-ravaged in a 27-17 defeat of Miami in Super Bowl XVII.

"The following year after that game, every time I turned on ESPN I saw it, the same play -- John Riggins running downfield (43 yards for a touchdown)," said Miami linebacker Earnie Rhone. "I want that out of my mind."

Soon after Miami had lost to San Diego (34-28) and the Los Angeles Raiders (45-34) late in the season, the Dolphins trailed Indianapolis at halftime. They had reached their defensive nadir.

"We walked in at halftime and said, 'God, what is happening to us?' said linebacker Charles Bowser. " 'We have to respect them as a football team, but they are only the Colts.' "

Miami rallied to win that game, 35-17, and players say that halftime defensive meeting, with Rhone playing the rouser, was a turning point. But can this defense slow Walsh's highly creative offense?

"It's like the media separates our team into Miami offense there, Miami defense here," Rhone said. "People compare us to San Diego, when Fouts scores 50 points and the San Diego defense gives up 51. That's not a fair comparison."

"The 49er offense is very diversified and tough to zero in on," Miami Coach Don Shula said. "The thing that scares you about Montana is something like what happened (in San Francisco's 23-0 NFC title victory over Chicago), when he scrambles for more than 50 yards. You preach containment to your players, but with Montana, that's hard."

The Dolphins' defense has yielded 4.7 yards per run this season, a near-fatal figure. "It's a valid stat," Shula said. "Our run defense has been a major concern."

And what of San Francisco's defense? It merely yielded the fewest points (14.2 average) in the league. Consider: this will be the third Super Bowl in which the league's No. 1 scoring offense plays the league's No. 1 scoring defense.

On both previous occasions, the team with the top-ranked defense has won: Green Bay over Kansas City, 31-10, in Super Bowl I and Pittsburgh over Dallas, 35-31, in Super Bowl XIII. Who says defense doesn't win Super Bowls?

Marino, who led Miami to 513 points and 70 touchdowns in the regular season, has been sacked just 14 times in 18 games. All-pro center Dwight Stephenson has been dead-ending blitzers all season. Pittsburgh tried and died by the blitz in a 45-28 loss in the AFC title game two weeks ago.

The Dolphins had been concerned they might have to play without tight end Dan Johnson, who missed practice Friday because it was feared he had appendicitis. Tests taken proved inconclusive, however, and Johnson has been cleared to play after spending a restful night at the team's hotel in Oakland and participating in Miami's final workout today. Shula said tight end Bruce Hardy will start, but Johnson would play.

It seems likely that the 49ers, who normally use a 3-4 alignment, often will shift to their "Elephant" defense (four-man front), inserting Dean and positioning him on either side. They also will add a fifth defensive back. This is one way to improve pass coverage against Miami's four-receiver formation, where Duper and Clayton run deep down the outside and tight end Joe Rose and receiver Nat Moore run down the hashmarks.

Also, San Francisco reserve safety Tom Holmoe likely will play often, in the nickel formation. Somehow, San Francisco must exert some pressure on Marino, make certain that running backs Woody Bennett and Tony Nathan don't slip past their containment and keep tight coverage on Duper and Clayton.

There are other elements to consider, of course. Certainly, the 49ers have an advantage in kickers, cool Ray Wersching (25 for 35 in field-goal tries) versus Miami's erratic Uwe von Schamann (nine for 19). And might the Dolphins try a no-huddle offense to offset the mass substitutions of the 49ers' defense, many of which come after the offense has broken huddle?

And what about Shula's Super Bowl experience? This will be his sixth (he's 2-3).

The weather is expected to be dry and partly cloudy, with temperatures in the low 50s, with winds of up to 20 mph expected at kickoff. Winds are expected to diminish later in the day, with temperatures dropping into the mid-40s late in the game. No rain is in the forecast.

How fitting that, in the end, it comes down to the only two teams that began this season 6-0. The 49ers' only loss came when Wersching shanked a 37-yard field goal in the final seconds of a 20-17 loss to Pittsburgh. Had Wersching converted, the 49ers might be 18-0 and already have become the first team ever to win 18 games in one season.

"I think it's good we lost that one," said linebacker Rikki Ellison. "We were getting too headstrong, too cocky."