LAS VEGAS -- Since taking over for Jimmy Garoppolo, rookie Brock Purdy has faced and passed a number of tests for the San Francisco 49ers.

But the one he got from the Las Vegas Raiders on Sunday was, perhaps, the most difficult yet.

The Niners faced a fourth-quarter deficit for the first time with Purdy as the starter, and nobody quite knew how he'd handle it. But as he's done with all the other tests, Purdy earned more high marks as the 49ers won a wild 37-34 shootout against the Raiders.

It was San Francisco's ninth straight win, its longest such streak since an 11-game surge in 1997.

Purdy became the first rookie quarterback to win four straight starts since Ben Roethlisberger went 13-0 in 2004. That he did it in a game in which the Niners got just their second win when trailing by double digits in the second half since Kyle Shanahan took over in 2017, left his coach and many of his teammates ready to say this is more than a flash in the pan.

"What Brock's doing is real," Shanahan said. "He's a talented guy who is very tough, and when he does make mistakes he understands why and then he tries to learn from them. He doesn't have a ton of experience in this league. So, every time he goes out there, whether it is good or bad, I feel like when you've got the skill set and play the game the right way, he's only going to get better from it. So, there was a number of situations that happened today that he didn't get in his other four games, and yes, I do think that helps."

Purdy finished 22-of-35 passing for 284 yards with two touchdowns and an interception for a 68.5 QBR. It was his fifth straight game with multiple touchdown passes, tied for the second-longest streak by a rookie since the 1970 merger (the Chargers' Justin Herbert did it seven straight games in 2020). And Purdy has thrown multiple touchdowns in each of the past five games, tying Dak Prescott circa 2016 as the only rookies to do that and win all five of those games in NFL history.

Perhaps most impressive was what Purdy was able to do in the fourth quarter. Entering Sunday, he had played a total of nine snaps with the 49ers trailing at any point in the five games he has been the primary starter. All nine of those came when he entered for Garoppolo with 9:30 left in the first quarter of the Dec. 4 win against the Miami Dolphins.

But Purdy was, according to teammates, unfazed by the scoreboard.

"I think just the type of player he is, the type of dude he is, how good he really, actually is and how calm he is and plays this game at the quarterback position, I feel like he's even kind of sped me up a little bit," receiver Brandon Aiyuk said. "Today just really showed us that I think this dude is on a different level and he can play for sure."

After falling behind 24-14, Purdy led four Niners scoring drives in regulation. On the final two, he was 6-of-10 passing for 113 yards, with one drive ending in Jordan Mason's rushing touchdown and another in a missed field goal.

Purdy, who said he hadn't played in a close-and-late situation since his time at Iowa State, credited Shanahan for his playcalling and his talented teammates for helping along the way. But he also didn't mind finally facing some game pressure.

"I don't have to go in feeling like the weight of the world is on my shoulders and I have to perform or else," Purdy said. "I've just got to go do my job. So, to have that kind of game, it was great to feel like that in the fourth quarter, the game is on the line and now we've got to go and put up points. It was great for me to go through that and feel it again."

With the win, the Niners leapfrogged the Minnesota Vikings for the No. 2 seed in the NFC playoffs. Although the teams have the same record, the Niners hold the tiebreaker by virtue of their better record in NFC games (9-2). San Francisco would wrap up the second spot with a win next Sunday against the Arizona Cardinals or a Vikings loss to the Chicago Bears.

San Francisco even has a shot at the No. 1 seed (and the bye and home-field advantage throughout the NFC playoffs) if it beats the Cardinals and the Philadelphia Eagles lose to the New York Giants in Week 18.

"I think it's real important," Shanahan said. "Our first goal is to get into the playoffs. I call it the tournament, and once you get there, you always have a chance for the ultimate goal. And everything about once you do get there is to position yourself the best way you can, and we don't know until we come in, but them just telling us and being able to tell the team that right now that we have the 2-seed if we can take care of business, I know that fires the guys up, and I think with Philly losing, it sounds like we've got a chance at the other one, too. Our playoffs started a long time ago is the way we look at it, and we're going to keep it going."