SEATTLE -- - Rookie quarterback Brock Purdy never doubted he'd take the field for the 49ers with a chance at winning a division title.
But how long Purdy would be able to play through his oblique injury lingered all night in the mind of San Francisco coach Kyle Shanahan.
"We were going to see how long he'd last and we were ready to go with (backup) Josh (Johnson)," Shanahan said. "But he just got comfortable and got better as the game went on. It's pretty unbelievable."
Purdy threw a pair of touchdown passes to George Kittle, and the 49ers won their first NFC West title since 2019, beating the Seattle Seahawks 21-13 on Thursday night.
Despite using their third starting quarterback this season, the 49ers (10-4) continued to show they might be the class of the NFC alongside Philadelphia. San Francisco won its seventh straight, using its stifling defense to frustrate Seattle into countless mistakes.
The Niners got a handful of big plays from their rookie quarterback, who didn't make any throws during the limited practice time leading into the game.
"My mindset was I was coming into this place to play and start. That was that," Purdy said.
Playing on the road for the first time in his career, Purdy connected on his first 11 pass attempts, including a 28-yard TD to Kittle in the first quarter when Purdy executed two fakes before hitting his tight end wide open.
The play was called "Hollywood" and was flawless in its execution.
"Whenever Kyle dials something up that you know you're gonna get the ball, you try to speak it into existence. So you got to say 'touchdown' and visualize it, and it was actually perfect," Kittle said.
Purdy and Kittle connected again early in the second half as Seattle's defense blew a coverage and left Kittle open for a 54-yard TD and a 21-3 San Francisco lead. Purdy finished 17 of 26 for 217 yards, joining Aaron Rodgers as the only QBs since at least 1950 to have a passer rating of at least 115 in each of their first two starts.
"Honestly my mindset was even though I haven't thrown a ball, I played four days ago," Purdy said. "So I know where guys are supposed to be. I know what it's like to rip a ball on rhythm and in tight on time."
Kittle had four catches for 93 yards and Christian McCaffrey rushed for 108 yards, including a 1-yard TD run in the final minute of the first half following a Seattle turnover.
Seattle (7-7) lost for the fourth time in five games and its playoff hopes took another hit. Geno Smith threw for 238 yards and Seattle's first offensive TD this season against the 49ers, but was under constant pressure.
Seattle pulled within one score late in the fourth quarter after Robbie Gould missed a 43-yard field goal and the Seahawks went 67 yards in 1:25. Smith hit Noah Fant on a 10-yard TD with 3:35 remaining. But Purdy converted a third-and-1 with a scramble before the 2-minute warning, and Jordan Mason sealed the victory with a 55-yard rush with 1:02 remaining.
"I don't know if I have all the right words. But man, I just hate losing and gotta figure it out," Smith said.
Smith was sacked three times and hit nine times. When he did have time to throw, open windows for his pass catchers were small. Seattle had one play longer than 20 yards, and wide receiver Tyler Lockett suffered a broken bone in his hand late in the game.
And Seattle missed taking advantage of a 49ers mistake late in the first half.
Seattle scored its first offensive points in two games against the 49ers midway through the second quarter on Jason Myers' 38-yard field goal. Seattle's only points in the first matchup in Week 2 came on a blocked field goal returned for a touchdown.
But the Seahawks followed with a pair of critical mistakes. Quandre Diggs dropped a potential interception that would have given Seattle the ball on San Francisco's side of the field. And Travis Homer fumbled on a big hit by Dre Greenlaw at the Seattle 41 with 1:08 left in the second quarter. The fumble was returned 35 yards by Charvarius Ward, and two plays later, McCaffrey scored to give the 49ers a 14-3 lead.
The 49ers have allowed 17 points or fewer in every game of their win streak.
"I think just from the first time we played them we knew we had an advantage, and we were going to have to take full advantage of it," 49ers defensive end Nick Bosa said. "We definitely did our job."
TRIUMPHANT IN SEATTLE
Shanahan also won his first division title at Seattle when San Francisco won the final game of the 2019 regular season.
GREEDY GREENLAW
Greenlaw has either a forced fumble, fumble recovery or interception in five straight games. He had eight tackles.
INJURIES
Seattle was without starting defensive tackle Al Woods due to an Achilles tendon injury and lost his backup Bryan Mone to a knee injury in the first quarter. ... San Francisco CB Ambry Thomas suffered an ankle injury. ... Seattle LB Jordyn Brooks (neck) didn't play in the fourth quarter. ... 49ers DE Samsom Ebukam limped off in the fourth quarter.
UP NEXT
San Francisco: Hosts Washington on Dec. 24.
Seattle: At Kansas City on Dec. 24.
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