INGLEWOOD, Calif. — As he addressed his team Saturday night, San Francisco 49ers coach Kyle Shanahan issued a stern warning about the type of opponent the Los Angeles Rams would be on Sunday.

Although the winless Rams were coming off an embarrassing loss to the Arizona Cardinals and were as depleted by injuries as any team in the league, Shanahan expected Los Angeles to play with plenty of urgency and desperation.

“You’ve got to take their hope away,” Shanahan said. “You give [Rams quarterback Matthew] Stafford too much hope [and] you put a ball in his hands at the end, it’s not a situation you want to be in.”

Alas, that was precisely the situation the Niners were in late Sunday afternoon. Despite jumping out to a 14-point lead, San Francisco was unable to build on its early momentum because of special teams miscues, defensive breakdowns and offensive errors on the way to a stunning 27-24 loss.

The Niners dropped their second consecutive game, falling to 1-2, and lost to an NFC West division opponent for the first time with Brock Purdy as the starting quarterback. After the game, Shanahan described his team as “pissed” at how a victory slipped away. That frustration was apparent in the locker room as wide receiver Jauan Jennings, who had nearly carried the Niners to a win with a career-best outing, declined to speak to the media.

“It was unacceptable,” linebacker Fred Warner said. “We can’t do that. We can’t beat ourselves. Can’t make those type of mistakes again. All three phases have got to play better. We’ll look at the tape, fix it and move on.”

A proud 49ers team that has been to at least the NFC Championship Game in four of the past five years has plenty to fix. The Niners entered Sunday without a trio of their best players — injured star running back Christian McCaffrey (Achilles tendinitis), receiver Deebo Samuel (calf) and tight end George Kittle (hamstring) — but the Rams felt little sympathy as they also are missing plenty of injured players.

For San Francisco, the game took a turn for the worse with 6:22 left in the second quarter and the Rams facing a fourth-and-6 from their 43. Down by two scores with little to lose, it was an obvious spot for a fake punt, so much so that Shanahan and the Niners called the punt return with the expectation of a fake.

It didn’t matter, as the direct snap to Rams running back Ronnie Rivers turned into a 7-yard gain and, eventually, the Rams’ first touchdown. Instead of a potential three-score deficit, the Rams were left with plenty of hope. That was only bolstered by continued San Francisco blunders on special teams.

After allowing a blocked punt in last week’s loss to the Minnesota Vikings, the Niners allowed the fake punt conversion, missed a 55-yard field goal and yielded a 38-yard punt return to set up the Rams’ winning field goal.

“That’s where I thought we had a chance to run away with it, not give them any hope,” Shanahan said. “That gave them a lot of hope. Got them back in it … those are three big plays in the game.”

Special teams wasn’t the only issue for the Niners on Sunday. A defense that held the Rams to zero points, 29 yards and one first down in the opening quarter allowed Los Angeles to post 27 points, 267 yards and 18 first downs over the final three. The Niners also did not force a turnover as Stafford authored his 45th game-winning drive in the fourth quarter or overtime, seventh most since the 1970 merger.

The 14-point comeback win is the largest by the Rams under coach Sean McVay and biggest overall since Week 2 of the 2012 season.

“I think we have to feel the loss,” end Nick Bosa said. “We can’t just move on and act like it’s fine … The NFL, it’s up and down, and no matter how talented you think you are, you have to play good on Sunday.”

Despite all of that, the Niners still had a chance to win, largely because of Jennings and Purdy. Starting in place of Samuel, Jennings delivered a game to remember with 11 catches for 175 yards and three touchdowns, becoming the fourth player in franchise history to have 175 receiving yards and three scores in the same game.

Purdy, meanwhile, didn’t miss a beat without his usual weapons, finishing 22-of-30 for 292 yards and three touchdowns with a 137.1 passer rating. But those numbers could have been better as Purdy didn’t get much help from pass catchers not named Jennings. The Niners were charged with three drops, though they had others wiped out by penalties.

None was bigger than the deep pass Purdy fired to an open Ronnie Bell down the right sideline with 1:08 to go. Purdy’s pass was on target and Bell had a clean chance at a big catch to set up a potential game-winning field goal. Instead, Bell dropped it and the Niners were forced to punt to set up the Rams’ final drive.

The loss made Purdy the third 49ers signal caller (alongside Joe Montana and Steve Young) to lose a game in which he completed at least 70% of his passes and three or more touchdowns. It also dropped the Niners below the .500 mark for the first time with Purdy as the starter.

At 1-2, the Niners are well aware that there is plenty of season left. Their locker room is full of players who have helped them dig out of even more difficult spots in the recent past. But they also know opportunities like Sunday’s can come back to haunt them later in the year.

“That’s just part of the NFL and being a professional in a professional sport, everybody’s really good,” Purdy said. “Last year means absolutely nothing. And every time you show up on Sunday, you’re going to get everybody’s best shot. It’s the NFL and we all have to be real with that. We have to have the mindset of going and taking it every Sunday and nothing’s ever going to be given to us.”