Their quarterbacks are plastered all over magazine covers, their defenses are elite, and their coaches are viewed as annoying by those outside their fan base. Even as their teams have evolved and personnel changed, the principles at the foundation of both franchises remain starkly the same.
"It's very similar scheme-wise and very similar in the way they put the teams together and the types of players," Seattle Seahawks receiver Doug Baldwin said. "They just want hard-nosed, tough players that are going to fight every day."
Week 2 may seem too early for this much hype and anticipation, but the Seahawks and 49ers understand the importance of Sunday night's NFC West showdown. The winner gets a leg up in both the divisional and the conference race.
Toss in the nasty history between coaches Pete Carroll and Jim Harbaugh's, the constant comparisons between quarterbacks Russell Wilson and Colin Kaepernick, and the debate about which team has the more fearsome defense and it's no surprise a West Coast rivalry is getting so much national attention.
The San Francisco 49ers have a bad taste from last December. Seattle scored on its second offensive play, got a 90-yard blocked field goal return for a touchdown from Richard Sherman and routed the Niners 42-13.
"We're going up there to try to prove that's not who we are," Kaepernick said.
Here are five keys to watch to the game:
STOP THE BIG PLAYS: Limiting explosive plays is one of the tenets in Seattle's defense. Last season, the Seahawks tied for sixth in the NFL allowing 50 plays of 20 or more yards. The longest play allowed in Week 1 against Carolina was a 27-yard pass, the only play longer than 16 yards. Conversely, the 49ers' offense started the season with nine plays of more than 20 yards, most of them connections between Kaepernick and Anquan Boldin or Vernon Davis. Boldin quickly became Kaepernick's favorite target with 13 catches for 208 yards, including receptions of 43, 30, and 22 yards three times.
WHERE'S THE READ-OPTION?: The big fad at the end of 2012 was the read-option offense that both Seattle and San Francisco used with success due to the athleticism of their quarterbacks. Kaepernick blitzed Green Bay for 181 yards rushing in the playoffs alone. It was the next step in offensive evolution.
So what happened in Week 1? Neither team displayed much of the read-option. Wilson rushed for 7 yards on five carries. Kaepernick was almost as reserved, carrying seven times for 22 yards.
COWBOY UP: 49ers defensive tackle Justin Smith did not play against Seattle last December, ending a streak of 185 consecutive games. His injured triceps finally forced him to the sideline that rainy night and his absence was noticeable. Early in the game, Seattle ran directly at Smith's replacement and tore up huge chunks of yards with Marshawn Lynch, who finished with 111 yards rushing. Smith's absence also allowed Seattle to block the rest of the 49ers defensive front straight up and helped keep Aldon Smith from harassing Wilson.
"He's a real steadying piece to how they play. He's so dominant physically," Carroll said of Justin Smith.
BEAST MODE: Since Harbaugh took over, the 49ers have allowed only five 100-yard rushing games by an individual back. Lynch has three of those. The Seahawks' run game sputtered out of the gate, gaining just 70 yards, 2.6 yards per carry, against Carolina, with Lynch gaining 43 yards.
"First game, we threw a lot out there and probably didn't just hone in on what we like to do," Seattle offensive coordinator Darrell Bevell said.
CAN YOU HEAR ME NOW?: A group led by former Seahawks player Joe Tafoya arranged for officials from Guinness Book of World Records to be there Sunday to see if Seattle can set a record for the loudest stadium.
It was already going to be a full day of anticipation — and likely inebriation — for Seahawks fans leading up to kickoff. Now, on top of being naturally loud, they'll be trying to set a record. To get ready this week, the 49ers cranked music at practice trying to simulate the constant rumble they'll face Sunday.
Bring ear plugs.
"It's tough," 49ers running back Frank Gore said of the noise. "We've got to go do it."
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