SANTA CLARA, Calif. (AP) - Linebacker Takeo Spikes figures there will be days this season when San Francisco's defense struggles and the offense carries the load.
The 49ers could afford an off day on offense in their season-opening win at Arizona thanks to the team's tenacious defense led by the regular cast of veterans like Spikes, Patrick Willis, Parys Haralson and Justin Smith.
San Francisco's strength last season appears to be its strength again: an aggressive unit that's had all the coaching continuity lacked by the offense. Coach Mike Singletary praised his regulars and an ever-improving secondary for its playmaking Sunday, too.
"I think it was just good to start off with a win and play well on the road in a hostile environment against a good offensive football team," Spikes said Wednesday. "But it means nothing at all if you can't come back and back it up, because in this league if you're not consistent you're just a one-hit wonder."
This week, the Niners defense will be tested in a different way trying to defend and adapt to Seattle quarterback Matt Hasselbeck's mobile, active style, which is far different from that of Arizona's Kurt Warner.
The speedy Seahawks will look to set the tempo from the start and test the 49ers defensive front by pounding the ball and running at every opportunity, more so in new offensive coordinator Greg Knapp's run-based, zone-blocking scheme than under former coach Mike Holmgren.
In last weekend's 28-0 win over the Rams, Julius Jones produced his first 100-yard rushing day since Week 3 of last season - 62 of that coming on a second-half touchdown run.
"To me, we just scratched the surface in the first week," Singletary said of his defense. "We have to continue to get better. ... We're going to have our hands full on the defensive side of the ball trying to defend what they do."
The play of the defense helped make up for a dismal running game that generated just 21 yards on the ground, a 49ers franchise-low in a victory and the third-lowest output in team history. Even Singletary was surprised his team beat the defending NFC champion Cardinals 20-16 with such a quiet day rushing.
There were plenty of deficiencies in the offensive line play that kept the Niners from effectively running the ball. Frank Gore had only 30 yards on 22 carries with a touchdown but also caught the 3-yard TD pass from Shaun Hill in the fourth quarter that helped seal the victory.
Singletary is calling for more from his O-line, saying it's back to fundamentals for that unit this week.
"We've got to give Frank a chance to get to the line of scrimmage and get those tough yards," center Eric Heitmann said. "That's something we can correct."
Meanwhile, the defense is determined to make a name for itself by wreaking havoc on opposing quarterbacks. The 49ers know they need to force more turnovers to turn this team back into a winner following a franchise-worst six straight losing seasons.
San Francisco managed only 12 interceptions in 2008 and tied for 16th in the NFL with 30 sacks. The Niners had three sacks and two interceptions in Week 1 and held star Arizona receiver Larry Fitzgerald to six catches for 71 yards and a long of 25.
The 49ers pressured Warner at times with a four-man rush, which allowed them to use more defensive backs and double-team Fitzgerald.
"I think it's a lot of momentum but we basically just go out and play our defense: 11 guys flying to the ball trying to make plays and help the team win," said Haralson, who had one of the sacks on Warner. "It's a good step in the right direction."
Seahawks coach Jim Mora was impressed with what he saw on film.
"I thought they tackled very well, I thought they attacked the football very well," Mora said Wednesday. "They played with great energy."
Spikes and his defensive teammates aren't about to start keeping track of the games their unit wins for the 49ers. Singletary has been preaching since he took over the job from the fired Mike Nolan last October the importance of competing together like a family, picking each other up and not worrying about individual feats.
"That's even more pressure for them because it's like, 'OK they're holding them, they're holding them' and we can only do it for so long," Spikes said of the offense. "There are going to be games that are going to be like that. Somebody else has to step up, which was us."
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