Once upon a time (and we're talking a mere two years ago), the Seahawks-49ers rivalry was must-see TV for the entire NFL.

Now it's just must-win TV for the Hawks and Niners, who both are 2-4 as they enter their game tonight in San Francisco. The loser can all but kiss the playoffs goodbye -- assuming Arizona (4-2) doesn't take a nosedive the rest of the way.

Pete Carroll's Seahawks are just 1-4 in Carroll's hometown of San Francisco, but that win came last season, when the Hawks won 19-3.

That win came at the beginning of a dominant defensive run for Seattle, which branded consecutive 19-3 losses on Arizona and San Francisco and finished with six straight wins to earn the NFC's No. 1 seed again.

Seattle can only hope the game in San Francisco tonight is the beginning of another such stretch of defensive dominance.

But, if the Seahawks are going to get on that same kind of run, they are going to have to figure out how to finish off teams. And that means the defense is going to have to figure out how to stop quarterbacks from carving it up, like Carolina's Cam Newton did in the fourth quarter Sunday.

Newton had played as poorly as usual against Seattle for most of three quarters; but, in the fourth quarter, he led the Panthers on two 80-yard TD drives to rally from what had been a 13-point deficit. It earned him his first win in five games against Russell Wilson's Seahawks over the past four seasons.

Newton just followed the lead of most of the other quarterbacks who have beaten Seattle's defense over the past few seasons: Throw short routes to running backs, tight ends and slot receivers.

Now the Seahawks face another Newton-esque passer in San Francisco quarterback Colin Kaepernick -- a similarly big, mobile quarterback who has not shown much consistency as a passer and has been dominated by the Seahawks over the years. Kaepernick is 1-5 vs. Seattle, with three touchdowns, nine interceptions, a 52.5 percent completion rate and a 53.7 passer rating.

However, the Kaepernick the Seahawks are facing tonight does not appear to be the same CK7 they have seen before or who started the season so poorly (two TDs, five interceptions in 1-3 start).  In the past two weeks, including a 25-20 win over Baltimore on Sunday, he has thrown for 602 yards, four touchdowns and no interceptions.

Of course, a lot of his plays the past two games have come via the deep ball -- an area where the Seahawks typically do not give up much. As Richard Sherman said, a lot of teams are attacking the Seahawks with short passes.

Asked about the state of the rivalry with the 49ers now that Jim Harbaugh is gone and both teams are scuffling through this season, Sherman said,  “It’s no different than it was then. It’s the same old, one game at a time. Another opponent, another opportunity to go out there and improve and show what we can do. They played very well last game, and we see some things that they do very well, and we’re going to do our best to stay on top of it.”

The question is whether they can stay on top of it for four quarters finally and get their second win in San Francisco under Carroll. They need it if they plan to start another big run toward the Super Bowl.

Sherman, for one, seems quite confident they will become the same team they have been the past two years.

He said the 2-4 hole is "not anything to be concerned about on our end. I think we’re a hard team to rattle, a hard team to get down, because we take it one game at a time. You don’t win all of the games, and I think sometimes these moments kind of help you improve as a team.

"I think we appreciate that. We appreciate how tough it is this year. We’re in a lot of these games. It would be a different story if we were getting blown out by 40 points every week and there was no way to fix it. But there’s one mistake, one play here or there that guys just need to clean up and correct, and we’re right on it.”

Image: Keith Allison (Flickr)