San Francisco 49ers rookies had their handprints all over Thursday’s road upset of the Rams. No one was noticeably dominant. But among the plays that decided the overtime thriller, a number of them featured the not-so-newbies as the Niners trudged to first place in the NFC West on the other end of a 26-23 win at SoFi Stadium.

All-Pro linebacker and team captain Fred Warner joked: “John Lynch probably gonna celebrate on the plane tonight.”

Down at the 1: The Rams possessed the ball with a fresh set of downs and the end zone merely three yards away to potentially seal a comeback win. The 49ers led 23-20 with only one timeout left. The clock read 1:07. Niners head coach Kyle Shanahan admitted after the game he and his staff discussed the possibility of letting the Rams score, which would’ve guaranteed their offense an opportunity to win or lose the game with the ball and avoid the risk of losing precious seconds.

“I mean, there was a thought,” Shanahan said. “We talked about it. But I wanted to hold them to a field goal.”

Rookie defensive tackle Alfred Collins made his job easier.

Rams running back Kyren Williams was steps away from scoring when Collins threw a right cross to the football. The ball jarred loose. Collins fell on it. And although his training camp and early returns this season left a lot to be desired, starting defensive tackle Kalia Davis had exited in the first quarter with a fractured hand. Collins, 6-foot-5 and 332 pounds, needed to shoulder a heavier load of snaps. He did more than take up space.

Collins, in a career-high 40 snaps, was the 49ers’ highest-graded defensive player (85.0) via Pro Football Focus among those who played at least 20 snaps.

“Since training camp, he’s been on an escalator,” left tackle Trent Williams said. “He’s constantly taking steps to improve. You can just see it in his assertiveness and the way he plays. Just the difference from July to now, it’s night and day. It’s funny because guys usually don’t take that big of a jump until they’ve had an offseason. … His progression is kind of scary.”

Walk it off: You won’t find defensive end Mykel Williams in the box score. You will see safety Marques Sigle toward the top with his team-high 13 tackles, albeit due in large part to how much he struggled in coverage. Williams did not record a single stat, reminiscent of his quiet NFL debut. Sigle was targeted seven times and allowed six catches for 138 yards, accounting for more than a third of Matthew Stafford’s 389 yards through the air.

Both hunkered down as key cogs on the play that secured their team’s win in walk-off fashion.

Williams cut inside Rams backup right tackle Warren McClendon Jr. in a way that carried McClendon out of the B-gap, opening up a clear path for Warner to burst through. Williams was therefore forced to bounce his run to the C-gap. Reserve nickel back Chase Lucas occupied a blocker in that hole. Sigle, along with cornerback Deommodore Lenoir, did what earned him the “Sultan of Swarm” nickname from the 49ers scouting department.

In-game injuries: Collins has a knee sprain that will be re-evaluated next week. Nickel back Upton Stout was replaced by Lucas late due to an ankle injury he suffered; Shanahan said Stout avoided a high ankle sprain and is day-to-day.

Briefly: Stout surrendered seven catches on eight targets for 86 yards with a 29.0 coverage grade that ranked second-to-last among eligible 49ers players; only linebacker Dee Winters finished with a worse coverage grade (28.4). … Connor Colby in his third start at left guard received poor PFF grading across the board, including a team-worst 39.2 overall grade, a 51.3 run-blocking grade and a 43.0 pass-blocking grade. He gave up one sack and four total pressures, and was flagged for three penalties. … Defensive tackle CJ West returned with a cast after missing one game. He was not credited with any box-score stats but tallied one hurry, per PFF, which assigned him a poor 29.8 overall grade.

Snap counts: Colby 86 (started), Sigle 68 (started), Williams 47 (started), Stout 38 (started), Collins 40, West 28, undrafted guard Drew Moss 6 (all on special teams).

Inactives:

• Wide receiver Jordan Watkins (calf): Watkins has been out of practice for more than two weeks.

• Running back Jordan James (non-injury): James has been a full practice participant for a few weeks now but has yet to make his NFL debut.

Practice squad: Return specialist Junior Bergen.

Reserve/non-football injury list: QB Kurtis Rourke (knee).