SEATTLE — Larry Grant never stopped pursuing and came up with the defensive play of the day when San Francisco needed it.

Grant tackled Seattle quarterback Tarvaris Jackson from behind, forcing a fumble that was recovered by Donte Whitner with 1:07 remaining, and the 49ers held on for a 19-17 win over the Seahawks on Saturday.

David Akers kicked four field goals for the 49ers, setting an NFL record with his 42nd of the season. He connected from 39 yards with 2:57 left to give San Francisco the lead.

The NFC West champions remained in position for the No. 2 seed in the playoffs and a first-round bye thanks to an impressive second-half effort on defense that was capped by Grant’s hustle play.

The loss eliminated Seattle (7-8) from playoff contention.

Frank Gore had a 4-yard touchdown run on San Francisco’s first drive of the second half.

Marshawn Lynch scored on a 4-yard run with 6:41 remaining to give Seattle a 17-16 lead. It was his 11th straight game with a score and the first touchdown rushing allowed by San Francisco (12-3) this season.

Lynch finished with 107 yards on 21 carries, the first back to run for 100 yards against the 49ers since Week 11 of the 2009 season.

San Francisco quarterback Alex Smith protected the ball as he has all season and his biggest throw set up Akers’ decisive kick. On second-and-18 from his own 31, Smith threw deep for Michael Crabtree, who got just enough separation from Brandon Browner to haul in the

41-yard reception. The 49ers didn’t advance any further, but were in range for Akers to give them the lead.

Smith finished 14 of 26 for 179 yards, while Crabtree had five catches for 85 yards. The bigger contributions came from Gore and his backup, Kendall Hunter. Gore finished with 83 yards rushing, while Hunter added 73 on just 12 carries.

The 49ers had 227 yards of offense in the second half and held Seattle to 72 yards. San Francisco coaches ran through the press box in the final seconds yelling, “Merry Christmas everybody!”

The 49ers could head into next week’s regular-season finale at St. Louis with the No. 2 seed locked up if Atlanta wins at New Orleans on Monday night. They are still alive for the No. 1 seed, but would need Green Bay to lose its final two games.

But all San Francisco needs is a win over the lowly Rams to clinch a home playoff game and a weekend of rest.

The 49ers were the first team in league history to go the first 14 games without allowing a touchdown rushing.

But Smith answered with his deep pass to Crabtree, and Seattle’s final chance was thwarted by the only turnover of the game.

Lynch’s 6-yard run to start the drive pushed him over the 100-yard mark, making him the first running back to top 100 yards against the 49ers since Ryan Grant did it for Green Bay in Week 11 of 2009. That snapped a streak of 36 straight games for the 49ers without allowing a 100-yard rusher.

Lynch then took a short pass from Jackson for 20 yards to the 45 at the 2-minute warning. Lynch added a 3-yard run and another swing pass to Lynch brought up third-and-3 at the San Francisco 48 with 1:18 left. Jackson was flushed from the pocket by Grant, who continued to pursue and grabbed Jackson from behind .The fumble bounced forward 10 yards, where Whitner fell on it as the San Francisco sideline burst into celebration.

Jackson finished 15 of 28 for 163 yards and a 13-yard TD pass to rookie Doug Baldwin in the first quarter.

Frank Gore charged up the middle with his signature burst for a 2-yard gain, taking another step forward in franchise history.

Gore got that coveted new contract and is playing like his old dominant self. Forget the hip injury that ended his season last November. He’s a new man making his case for a third Pro Bowl and pushing his team toward its first playoff berth in nine years.

Gore ran for both 125-plus yards and a touchdown in a fourth straight game, Michael Crabtree made his first TD reception of the season, and the San Francisco 49ers beat the Cleveland Browns 20-10 on Sunday.

Alex Smith completed 15 of 24 passes for 177 yards, leading the first-place 49ers (6-1) to their fifth consecutive victory since an overtime loss to the Cowboys in Week 2.

For Colt McCoy and the Browns, it’s 0-for the Bay Area. They lost two weeks ago in Oakland, then flopped across San Francisco Bay at Candlestick Park.

No handshake flap this time for Jim Harbaugh, either. And no post-bye letdown for his 49ers — even if it was far from flashy.

This marked Harbaugh’s first game since his seconds-long greeting and firm backslap of Lions coach Jim Schwartz following San Francisco’s 25-19 comeback win at Detroit two weeks ago.

Harbaugh says he practiced during the bye week by high-fiving with his toddler daughter. He was polite to fellow first-year coach Pat Shurmur when they met at midfield.

The 49ers — who were made aware by Harbaugh this week that teams were 3-9 after their byes coming into Sunday — are off to their first 6-1 start since 1998 in the days of greats Jerry Rice, Terrell Owens and Steve Young.

Cleveland’s D’Qwell Jackson committed a costly facemask penalty against Gore that would have stopped San Francisco on third down 2 yards short in the waning minutes. David Akers sealed it with his second field goal of the day, a 26-yarder.

Gore already had 103 yards on 19 carries by halftime, then got the other 7 yards he needed to pass Roger Craig and move into second place on the franchise rushing list with 7,089. Gore wound up with 134 yards on a season-high 31 carries.

San Francisco has a five-game winning streak for the first time since 2001 and wrapped up its first unbeaten October since 1997.

The next big task will be ending an eight-year stretch of frustration in which the team hasn’t had a winning season or made the playoffs. The Niners began the day with a comfortable three-game cushion in the division — nicknamed the NFC Worst last season, when Seattle won with a 7-9 record.

Harbaugh’s big brother, John, helped the sibling cause by rallying to beat Arizona 30-27 earlier Sunday.

The banged-up Browns (3-4) improved on special teams but went without their top two running backs. Peyton Hillis didn’t play for the second straight game because of a hamstring injury and Cleveland then lost Montario Hardesty to a calf injury in the first half.

McCoy and Co. managed only Phil Dawson’s 52-yard field goal on the final play of the first half before Josh Cribbs’ 45-yard TD catch with 6:17 to play.

After last week’s lackluster 6-3 win over the Seahawks, it didn’t get much better for the Browns. They failed to reach the end zone for seven quarters before Cribbs scored.

McCoy accounted for four of Cleveland’s five fumbles, one of which was lost and helped set up Gore’s early TD run.

McCoy lost the ball on the second play from scrimmage after he was stripped by Ahmad Brooks. Isaac Sopoaga recovered at the Cleveland 20. Gore ran 4 yards for the first points. Gore rushed for a touchdown in his fourth straight game, the first time in his career he’s done so.

McCoy was sacked four more times after five last week by the Seahawks.

San Francisco’s lopsided first half told the tale far before the clock finally wound down on a crystal-clear, unseasonably warm fall day.

First downs: 15-6. Total yards: 253-93. Time of possession: 18:58-11:02. Rushing yards: 145-25.

Crabtree caught a 2-yard pass to put the Niners ahead 17-0 just before halftime. Dashon Goldson made his first interception of 2011 in the end zone in the third quarter.

Left tackle Joe Staley even was in on the action, catching a 17-yard pass from Smith for a first down midway through the first quarter for his first career reception. He jumped up in celebration and signaled the first down by emphatically pointing down field with both hands. Sopoaga had an 18-yard reception late against the Browns’ fourth-ranked defense.

49ers wideout Braylon Edwards returned against his former club in his first action since right knee surgery after getting hurt against the Cowboys. He had four catches.