San Francisco 49ers quarterback Jimmy Garoppolo (10) throws against the Arizona Cardinals during the second half of an NFL football game, Thursday, Oct. 31, 2019, in Glendale, Ariz. (AP Photo/Rick Scuteri)

SANTA CLARA, Calif. (AP) — For most of the season, Jimmy Garoppolo hasn't been asked to carry too heavy a load at quarterback for the San Francisco 49ers thanks to a dominant defense and big-play running game.

The fact that Garoppolo was able to step up last week when those two facets weren't performing as usual is a good sign for San Francisco heading into the much more difficult second half to the season.

The Niners (8-0) know they will need more games like that one at Arizona from their franchise quarterback if they are going to make a playoff run.

"I was very impressed," coach Kyle Shanahan said Thursday. "I thought he played his best game of the year. He made a lot of really good throws in rhythm and made a lot of off-schedule throws where he had to move in the pocket and generate some plays on his own. It was a very impressive game and it would have been very tough to win that game if he didn't play that way."

Garoppolo will try to build on that Monday night when San Francisco hosts Seattle in the most meaningful matchup between these rivals in five years.

Garoppolo made his 49ers debut against the Seahawks nearly two years ago, when he replaced an injured C.J. Beathard in the closing seconds of a 24-13 loss. Garoppolo completed his first two passes for San Francisco in that game, including a meaningless touchdown to Louis Murphy.

But he wasn't able to play against Seattle last year after injuring his knee in Week 3 and will make his first start in the NFC West rivalry this week.

"It seems like a lifetime ago," Garoppolo said of his Niners debut. "It's a great group year in and year out. They're always one of the top teams and it'll be a great challenge for us."

Garoppolo will be the sixth quarterback to start for San Francisco against Seattle since the start of the 2014 season, joining Colin Kaepernick, Blaine Gabbert, Nick Mullens, Brian Hoyer and Beathard.

Wilson has started all 10 games for the Seahawks in that span, a main reason why Seattle has lost to San Francisco only once in the past 11 meetings thanks to better quarterback play and strong defense.

"They start with coverage," Garoppolo said. "The blitz has shown up more this year and everything, but they're always a coverage-first team it seems like. It's similar to what they've done in the past. They've had a couple change ups this year with new personnel and everything, but same old same old."

Garoppolo has the highest completion percentage (70.8 and passer rating (100.6) in his three seasons with the 49ers but he has been almost a complementary player at times this season on an offense running the ball a league-high 55.9% of the time. Garoppolo threw 25 or fewer passes in three of his first seven starts and didn't reach 300 yards once in that span.

But San Francisco needed a lot more from Garoppolo last week at Arizona when the defense was gassed in the second half and the running game stalled.

Garoppolo went 28 for 37 for 317 yards and no turnovers, while posting San Francisco's second four-TD game in the past 16 seasons. He was at his best on key downs, going 13 for 15 for 160 yards and all four of his TD passes on third or fourth down.

"Jimmy is awesome," new teammate Emmanuel Sanders said. "He doesn't have an ego. He comes in and works his butt off. He's a high energy guy. He's the type of person you enjoy being around."

NOTES: The 49ers signed K Chase McLaughlin after Robbie Gould injured his quadriceps Tuesday. Shanahan said there's still a chance Gould plays Monday night. ... T Sam Young was released to make room on the roster. ... TE George Kittle missed practice with injuries to his knee and ankle and his status for this week remains in doubt. ... CB Ahkello Witherspoon (foot) was not ready to return to practice yet. ... T Joe Staley (leg), T Mike McGlinchey (knee) and FB Kyle Juszczyk (knee) all practiced on a limited basis and could be back on the field this week.

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