The San Francisco 49ers need one win to clinch their second straight NFC West title.

Getting that done this week will mean doing something no other team has this season -- winning in Seattle.

The 49ers' top-ranked scoring defense could be in for a major test Sunday night when the high-scoring Seahawks will try to clinch their second playoff berth in three seasons and stay in the West race.

San Francisco (10-3-1) could have found itself in danger of letting the division lead slip away in Seattle after the Seahawks ripped Buffalo 50-17 at Toronto on Sunday, but instead turned in an impressive performance in their first of back-to-back prime-time contests. The 49ers built a 28-point lead at New England and hung on for a 41-34 win over the AFC East champs, clinching a playoff berth.

"Our team has now hung in in a lot of big-time pressure games," said coach Jim Harbaugh, whose team is in the driver's seat over 10-4 Green Bay for the NFC's No. 2 seed. "They've overcome adversity. They've shown they can do that."

The 49ers, though, have yet to show they can win three in a row this season, going 0-3-1 in their previous four chances. San Francisco has won four straight in this divisional matchup following a 13-6 victory on Oct. 18, but the Seahawks (9-5) are a much different team now with three consecutive wins and five in six games.

"The Seahawks are a hot team right now," 49ers quarterback Colin Kaepernick, who threw four TDs in Foxborough to earn NFC offensive player of the week honors, told the team's official website. "Their defense is playing great. Their offense is putting up points. So we have to be ready."

San Francisco's defense is the best in terms of points allowed (15.6 per game, one total point less than the Seahawks) and second in total yards (293.0), but Seattle's offense has been clicking lately. After setting a team record for points in a 58-0 win over Arizona on Dec. 9, the Seahawks became the first team in 62 years to score at least 50 points in consecutive weeks.

Their 108 points in those contests is tied for the third-most over a two-game stretch.

"We're definitely clicking well," said quarterback Russell Wilson, who ran for three scores and threw for another against the Bills. "I've been on a couple of teams that have scored that many in college. But to do it in the National Football League, I mean that's really tough to do."

No rookie QB since the 1970 merger had won his first six home games, but that's exactly what Wilson has accomplished.

Since he posted a season-low 38.7 passer rating in the loss at San Francisco, Wilson has completed 66.3 of his passes for 13 TDs with just two picks and a 111.3 rating.

Seattle is averaging 33.4 points in those contests -- second only to the Patriots' 41.3 during that stretch.

"I'm just thrilled that (Wilson's) been able to continue to grow," coach Pete Carroll said. "For a time, we were just trying to get the offense going and not screw it up and make sure he could keep growing.

"Well, we're past that now."

While Wilson and Marshawn Lynch -- who is 121 yards shy of becoming the third Seahawk back to reach 1,500 -- deserve much of the credit for Seattle's improved offense, the defense has been equally as impressive. This unit has allowed 14.2 points per game and forced 17 turnovers during this 5-1 run.

Seattle has been winning without cornerback Brandon Browner, who's served half of a four-game suspension for using performance-enhancing substances, but the news could get worse. Teammate Richard Sherman will have an appeal of the same suspension heard Friday, and if he loses it, he could also be forced to sit as soon as Sunday.

The Seahawks could also be without cornerbacks Walter Thurmond and Marcus Trufant, both of whom are nursing hamstring injuries. Should they be unable to go, Seattle would be down to rookie Jeremy Lane, Byron Maxwell and Ron Parker in the secondary.

Those absences figure to make it more difficult to keep 49ers wide receiver Michael Crabtree in check. Crabtree has 23 receptions for 301 yards and two TDs in the last three contests.

The 49ers rank second in the league with 162.9 yards per game on the ground, but leading rusher Frank Gore hasn't totaled 100 since running for a season-best 131 against Seattle.

If the Seahawks win, they'll still have a chance to win the West. Even with a loss, Seattle can clinch a playoff spot Sunday with losses by the Bears, Vikings and Redskins.

"It's a big division finish for us and we'll see how it goes," Carroll said.

"All we can do is focus on this game right here. We'll have no trouble focusing. They're a great team and coming home and all that it will be exciting to get ready."

San Francisco was the last visitor to win in Seattle with a 19-17 victory last Dec. 24.