SANTA CLARA — Minnesota has been a house of horrors for the San Francisco 49ers for decades.

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The Niners’ eighth straight loss in the Twin Cities looked an awful out like the one a year ago. The Vikings flummoxed Brock Purdy with their pressure packages and burned the San Francisco defense with a big passing play.

It added up to a 23-17 victory for the Vikings on Sunday that left the 49ers still searching for their first win at Minnesota since 1992 and was a big letdown following a season-opening win against the New York Jets.

“It’s a wake-up call but we know why it happened,” defensive end Nick Bosa said. “There’s a lot to fix.”

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What’s Next

San Francisco plays its first divisional game of the season on Sunday when the Niners visit the banged-up Los Angeles Rams.

Problems Across All Aspects of the Game

The problems for San Francisco (1-1) came in all aspects of the game. There was a special teams blunder in the first half; the defense gave up a 97-yard TD pass from Sam Darnold to Justin Jefferson and struggled to get off the field on third downs; and the offense managed just 17 points for the second straight year against coordinator Brian Flores’ defense.

Purdy looked uncomfortable for much of the day as he struggled with the heavy blitz package from the Vikings without his best outlet option in All-Pro running back Christian McCaffrey, who is injured.

“That’s what the point of the scheme is,” coach Kyle Shanahan said. “It’s to have six guys up on the line and come from everywhere. So it’s just a lot of pressure on a quarterback throughout a game. That’s what their scheme is. … It makes it really tough to get into a rhythm.”

What’s Working

The running game. With McCaffrey hurt, the Niners are thriving behind former undrafted free agent Jordan Mason. After rushing for 147 yards and a touchdown in the opener, Mason ran for 100 yards on 20 carries with a TD on Sunday. He joined Willie Parker (2005) as the only undrafted players since at least 1948 to rush for at least 100 yards and a TD in each of the first two games of a season.

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What Needs Help

Third down. San Francisco struggled in both aspects of third-down play, converting 2 of 10 chances and allowing Minnesota to convert 7 of 12. This was the first time in nine years that San Francisco converted 20% or less on third down and allowed the opposition to convert at least 55%.

The Niners have allowed opponents to convert 59.1% on third down this season — second worst in the NFL and the worst for the 49ers through two games since at least 2000.

“Big part of the game, third down,” Bosa said. “That’s why we have a whole day based on third down. That’s how this league is. We failed.”

Stock Up

Fred Warner. The All-Pro linebacker is off to a strong start. He followed up his forced fumble in Week 1 with an all-around performance that kept the Niners in the game. He had an interception in the second quarter that prevented a scoring chance and forced a fumble at the 1 in the fourth quarter to keep the game within reach. He finished with nine tackles and added a sack for his second game in the past two seasons with at least one sack, one INT and one forced fumble.

Stock Down

Special teams. Mitch Wishnowsky had a punt blocked in the first quarter to set up a field goal for Minnesota. Rookie Jacob Cowing then muffed a punt in the third quarter, but teammate Isaac Yiadom recovered to avoid a turnover.

Injuries

WR Deebo Samuel strained a calf in the game and will miss a couple of weeks. … S Talanoa Hufanga could return this week for the first time since tearing his ACL last November.

Key Number

3.31 — Purdy and the Niners’ offense are struggling when teams bring extra rushers, averaging just 3.31 yards per drop-back so far this season against five of more pass rushers, according to Sportradar. San Francisco gained just 73 yards on 19 drop-backs against extra rushers on Sunday with four sacks and one INT. Purdy led the NFL with 9.18 yards per drop-back against five or more pass rushers last season for the fifth best mark since 2012.