SANTA CLARA -- Jim Harbaugh was lighthearted and loquacious about every possible topic on earth Monday, except the Seattle Seahawks.

There was a good Harbaugh reason for this, of course, and this was great Harbaugh Theater, anyway. 49ers-Seahawks has turned into the NFL's best and most passionate rivalry, and Harbaugh clearly has no desire or need to add to it now that the two teams are set to resume it Sunday in Seattle.

Huge game. Lots of fascinating angles. No extra podium-fluffing necessary, at least at this point.

So Harbaugh spoke colorfully and pointedly about Green Bay linebacker Clay Matthews' actions in the 49ers' season-opening victory a day earlier, suggesting Matthews' "slap" of 49ers left tackle Joe Staley was less than manly.

The San Francisco 49ers head coach Jim Harbaugh reacts to a touchdown against the Green Bay Packers in their NFL game played at Candlestick Park in San
The San Francisco 49ers head coach Jim Harbaugh reacts to a touchdown against the Green Bay Packers in their NFL game played at Candlestick Park in San Francisco, Calif., on Sunday, Sept. 8, 2013. (Dan Honda/Bay Area News Group) (Dan Honda)

"If you're going to go to the face, come with some knuckles, you know? Not an open slap," Harbaugh said of Matthews' second-quarter striking of Staley.

"I think that young man works very hard on being a tough guy. He'll have some repairing to do to his image after the slap."

Harbaugh was defending his guys, zinging an opponent and also deflecting the onslaught of Seahawks talk, all at once.

Even more, the 49ers coach waxed eloquent about Colin Kaepernick, Anquan Boldin and many other things in a much more vivid and direct manner than he does on most days.

But when Harbaugh was asked about the Seattle matchup and the emotional series split last season, he detoured far away from any semblance of lively rhetoric.

"It's football, it's competition, it's winning," Harbaugh said blandly.

"There (are) good football teams that we're playing right out of the blocks here. And Seattle's an outstanding football team, and it'll be a great test for our team.

"We know there are challenges ahead of us."

Come on, it's Seattle Week. Harbaugh vs. Pete Carroll, a fevered personal matchup that goes back to Stanford vs. USC.

And now two franchises that cannot stand each other -- and have looked down on each other over various off-field indiscretions -- and are vying for NFC supremacy.

You're saying it's too early to talk about playoff implications in this loaded division?

"It's a free country," Harbaugh said with a smile. "You can talk about whatever you want."

Last year, the 49ers beat the Seahawks in a physical low-scoring meeting at Candlestick, then traveled to Seattle on the second-to-last weekend of the season -- in Kaepernick's sixth start -- and got thrashed, 42-13.

The 49ers made it to the Super Bowl anyway; the Seahawks got through the wild-card round, then lost in Atlanta in the divisional round.

Now they're co-favorites to win the NFC this season, which means the Road to the Super Bowl likely goes through either San Francisco or Seattle, depending on these two regular-season games.

(And there might be a third meeting in the postseason.)

This is Round 1, no added emphasis needed. Round 2 comes Dec. 8 at Candlestick.

Jim, do you enjoy having such a passionate rival?

"Yeah, always have," Harbaugh said. "I think it always raises the bar for both teams."

For the 49ers and Seahawks, the entirety of last offseason has seemed like a double bar-raising.

The 49ers acquired Boldin, then the Seahawks got Percy Harvin (who got hurt); the 49ers prepped their young QB for superstardom, and the Seahawks moved Russell Wilson into that category, too.

The 49ers have a great defense and bolstered it this offseason. Seattle: ditto and ditto.

The 49ers just outraced the Packers at home. Seattle survived in Carolina.

Everything is set up for Sunday night.

Yes, these franchises probably have the deepest and best two rosters in the league and presumably will be vying for playoff positions far into the future, starting Sunday.

"Well, we always look at the next game as the most important game of the year," Harbaugh said. "Winning that game, whatever the next game is, is the most important game on the schedule."

Whatever that game is. Who is it again? Oh, it's Seattle. That means Harbaugh can smile and joke, but he won't be talking much about the Seahawks.

Because everything that needs to be said or done will happen on the field between these two teams, maybe three times this season.

Read Tim Kawakami's Talking Points blog at blogs.mercurynews.com/kawakami. Contact him at tkawakami@mercurynews.com.

INSIDE

49ers coach Jim Harbaugh says Clay Matthews' image in need of repair. PAGE 3

Sunday's game

49ers (1-0) at Seattle (1-0), 5:30 p.m. NBC