Adam Thielen sparked some early electricity for the Vikings at San Francisco Sunday.

Thielen capped Minnesota's second and fourth possessions of the game with touchdowns—the 48th and 49th of his career.

He moved into fifth on the Vikings receiving touchdowns leaderboard but left the Bay Area in disappointment after a 34-26 loss to the 49ers.

Thielen's first score followed an interception by a Harrison Smith and converted a fourth-and-goal at the 2. Thielen had been involved on a key play earlier in the drive.

Vikings Offensive Coordinator Klint Kubiak implemented a flea-flicker on second-and-9, and Kirk Cousins executed. He handed off to Dalvin Cook, who then flipped it back to Cousins for a deep throw to Thielen down the left side of the field. The play gained 29 yards and set up first-and-goal.

Cousins handed off to Cook for consecutive runs that gained 3 and 1 yards, respectively, and his third-down pass to Justin Jefferson was incomplete.

Vikings Head Coach Mike Zimmer kept with the aggressive approach he's shown the past few weeks and opted to keep the offense on the field for fourth down.

It proved the right decision, as Cousins connected with Thielen in the back of the end zone, moving the receiver into a tie with Kyle Rudolph with 48 career receiving scores. The 2-yard touchdown, followed by Greg Joseph's extra point, gave Minnesota a 7-0 lead.

The 49ers answered with a score of their own, and the Vikings went three-and-punt on their third possession of the day. But they started out the second quarter in a big way.

Cousins showcased Jefferson and Thielen en route to another touchdown by the latter.

Jefferson totaled 45 yards on back-to-back catches, and on second-and-3 from the 20, Cousins faked the handoff, rolled out to his right and fired to Thielen. The receiver made a diving grab in the paint to give Minnesota back the lead.

Sunday marked Thielen's eight career multi-receiving-TD game, which is the most by a Viking since his debut in 2014 and is tied with Sammy White for third most in franchise history.

It seemed Thielen – and Jefferson – had given Minnesota's passing game life, but the offense fizzled at key moments.

The Vikings punted for a third time midway through the second quarter, and the 49ers embarked on a drive that lasted 8:20 and culminated with a Jauan Jennings score. The NFC foes entered halftime tied at 14 apiece, and Minnesota just couldn't get much going the rest of the day.

San Francisco started the third quarter on offense and bagged a second touchdown by Deebo Samuel. And when the Vikings looked to respond? Cousins threw a pass to Thielen that was easily intercepted by 49ers linebacker Azeez Al-Shaair.

Cook and Jefferson recorded gains of 30 and 15 yards, respectively, on the next Vikings possession capped by a 6-yard Alexander Mattison score.

After a Joseph PAT that pulled wide right, it seemed nothing could go quite right for the Vikings offense.

Rookie Kene Nwangwu boosted Minnesota with an explosive, 99-yard kickoff return following a 49ers field goal, but a 2-point conversion attempt fell flat – literally – with a much-to-low pass from Cousins to Jefferson.

"A poor throw," Cousins later said. "It felt like maybe I rushed it."

Just before the end of the third quarter, a scary-looking Cook injury resulted in a fumble that San Francisco recovered.

The Vikings kept fighting but to no avail.

A fourth-quarter deep pass to Thielen appeared to be hauled in by the receiver, who right away signaled a catch, but it was ruled an incompletion. Zimmer doubled down on Thielen's confidence by challenging the play, which the FOX broadcast booth expected to be overturned, but the officials upheld the initial call.

That play was the final pass of the game to Thielen, who ended the day with five catches for 62 yards and two touchdowns.

Jefferson led Minnesota in receiving yards with 83 on just four catches, averaging 20.8 per reception and eclipsing the 1,000-yard mark for the season, and Cook added six catches for 64 yards. Cook also had 10 carries for 39 yards rushing before leaving the game.

The Vikings never gave up, but things didn't go their way.

"I'm sure it's a variety of reasons," Cousins said. "You know, the turnovers don't help. I think it starts there, and ... we're so close. We've just gotta hit those plays in the red zone down there and come down with a touchdown. We're right there. It's just, we didn't make enough plays."

Minnesota had one last opportunity with two minutes and no timeouts remaining. Cousins connected with K.J. Osborn for a gain of 5 and Jefferson for 23. Cousins later targeted Osborn again over the middle on third-and-8. Officials didn't call a seemingly flagrant defensive pass interference penalty by cornerback K'Waun Williams, and a fourth-down attempt by Cousins went over Jefferson's head.

Asked about the no-call following the game, Zimmer said:

"Yeah, I thought he hooked him. I thought the defender hooked him."

Zimmer lamented the loss but praised his players' overall effort in a battle that – once again – came down to the wire.

"Well, from being around this team all year long, they've had a lot of times where they've had opportunities to let something affect them, and they just come out the next week and they play their rear ends off," Zimmer said. "There's been a lot of ups and downs, and I think that, you know, I'm proud of their effort. They played hard. I'm proud of their effort. We didn't get the win, so there's no consolation prizes, but I'm proud of the way they competed."

It's rare to see Jefferson without a smile, but the receiver wasn't wearing the signature grin postgame and didn't mince words in describing his feelings.

"It's very frustrating. Any time we're that close and don't win," Jefferson said. "I mean, we feel like we have the playmakers to get in the end zone. We feel like we have a good enough offense to drive the ball and score. We're frustrated every single time.

"I don't like to lose. I'm a competitor," he later added. "I love to win. I love this game, so any time we don't come out on top and we fall short, especially because we feel like we didn't play the game that we wanted to, it's always frustrating."