Once more, the San Francisco 49ers return to their crucible.

(Cue up the ominous NFL Films dum-dum-de-dum music.)

Once more, the 49ers journey to the place where they have endured so much sorrow, strife and abuse from strange mammals who sit on bleacher seats and love to wear large plastic wedges of cheese atop their heads.

(Dum-de-de-dum-de-dum-dum-dum-DUM)

Take a look at the 49ers' schedule. With a 4-5 record and seven games remaining, do the math. They need nine or 10 victories for a playoff spot. They won't be eliminated with a loss. But they really need to win today. They need to win in the worst way.

And they need to do it in the worst place possible for them.

Lambeau Field, for nearly 20 years, has been the stadium where 49ers hopes die and dissolve into a haze of bratwurst tailgate smoke and Wisconsin polka music.

(Ooom-pah, ooom-pah, ooom-pah.)

In 1990, Joe Montana triggered a 24-20 victory over the Packers on a fine autumn afternoon. Since then, the 49ers have played six games at Lambeau. They have lost all six.

Each defeat carried dreadful consequences, including the ouster of one coach and the tripwire for another's slide. And they all happened at Lambeau. An eerie coincidence? Cruel fate? Or simply the sinister curse of America's Dairyland?

(Moooo-pah, Mooo-pah, Mooo-pah.)

(All right, no more stupid music. Promise)

The truth is, over the past two decades, losses at Lambeau have often served to define a 49ers season. And never in a good way.

On their last visit, for example, the pregame circumstances were much like this one.

In November 2003, the 49ers showed up in Green Bay with a new coach (Dennis Erickson) and a recently promoted quarterback trying to make an impression (Tim Rattay). The team had a hopeful 5-5 record and still possessed playoff ambitions. But on a dank and overcast day, the Packers ran the ball down the 49ers' throats and won 20-10.

The 49ers went on to finish 7-9 and began their ongoing streak of five losing seasons. Erickson lost 17 of his next 21 games and was fired. So you might say that was a pretty bad watershed loss.

Although it might not have been as awful as the January 2002 playoff game when the Packers beat up the 49ers and ruined their first postseason appearance since the 1999 season.

And that game wasn't as wretched as the depressing 1997 season playoff loss that resulted in George Seifert deciding to "resign" as coach less than two weeks later.

Whew. That's an awful lot of awfulness — although Brian Jennings, the 49ers' current long snapper who played in the 2003 game, has his own theory about all this.

"To me, it was Brett Favre who just had a passion about playing and beating the 49ers," Jennings said. "If you look back at it, he was always really motivated for games against us. So to me, it's been more of a Brett Favre thing."

Favre, of course, has left for an even colder place (Minnesota, where he beat the 49ers earlier this season). But his replacement has been Aaron Rodgers, who has his own bitter reasons to stick it to the 49ers. And the storied Lambeau setting is still the same. The claustrophobic bowl that amplifies crowd noise is still the same. The Schnapps-fueled fans are still the same. The mojo is still the same.

And yet, Lambeau is not nearly as intimidating a place as it once was. The original stadium, built in 1957 — just three years before Candlestick Park — was a bare-bones structure with open end zones that allowed the cold breezes to blow across the field and bore into the players' flesh.

However, in 2003, the Packers gave Lambeau a major renovation. A row of luxury boxes now graces the entire stadium rim, above an annexed atrium that more resembles a shopping mall than a gridiron monument. If Vince Lombardi came back to visit, he could dine at the food court. And as for the so-called "frozen tundra," well, it's a myth. Heating pipes beneath the turf keep it plenty warm.

"I remember going out for pregame in 2003," Jennings said, "and the fans were yelling, 'frozen tundra, frozen tundra' and making fun of us for being from California. I thought, 'Don't they know this field is heated? And that our home preseason games at Candlestick always feel like it's 38 degrees?'"

The Packerland forecast on Sunday is for relatively clear skies with temperatures in the 40s. So there will be no weather-related excuses for the 49ers. Earlier this season, they came very close to beating the Vikings and Colts on the road. The Packers aren't as good as Minnesota or Indianapolis. So the opportunity is there. If this is yet another watershed game for the 49ers — and it is — then they must make sure they come down on the right side of the watershed.

"It's a big test for us — offense, defense and special teams," Jennings said.

He didn't mention the test of vanquishing the Lambeau voodoo.

(Dum-dum-dum-dum-DUM-DUM-DUM-DUM.)

(Sorry. Couldn't keep the promise.)