SANTA CLARA, Calif.— The Panthers' defense did everything possible to keep Carolina in Monday night's game. For a half, they were everywhere, haunting Brock Purdy from across the middle, and in the end zone.

"The defense battled, and they kept us in it, gave us some opportunities there," said coach Dave Canales.

But in the end, it wasn't enough, as the Panthers fell 20-9 to San Francisco.

"Our defense was putting us in some great situations with the interceptions and (offense) not coming away with points…those things really hurt us," said Canales.

After the 49ers jumped out to a quick 7-0 lead on their first drive, the defense clamped down. The next three San Francisco drives ended with Panthers' interceptions. Two of them were by Jaycee Horn . This was Horn's second multi-interception game in his career, the first coming earlier this year against the Jets in Week 7.

"My dude came out and played like he's—I think he said this is his first time playing on Monday night prime time, lights was bright, he showed up, showed the world who he is," said cornerback Mike Jackson about his teammate, joking he had to catch up since he only has two interceptions this season, and Horn now has five.

Asked what kind of level Horn is playing at right now, safety Tre'von Moehrig quickly answered, "All-Pro. And he's been like that all season, especially in my eyes."

Horn's first interception came when Brock Purdy tried a deep shot down the middle. Horn read it, jumping Jauan Jennings, center fielding the ball, and returning it 14 yards to put the offense in the red zone. The offense was unable to punch it in after Young threw an interception from the 1-yard line.

But the defense wasn't done. The next 49ers possession, a methodical 12-play drive that worked its way into Carolina territory, ended when Purdy again heaved one down the middle of the field, intending it for Ricky Pearsall in the end zone. But Jackson jumped in front of Pearsall to save the score and give the Panthers the touchback.

"I seen Purdy looking, so it was like once the ball was up, I was just like, go get it," said Jackson of the play.

The offense punted on the ensuing drive. So Horn went and got the ball back again. Purdy, in his second game back from a toe injury that kept him sidelined from Week 4 to Week 11, once again went deep over the middle. And Horn once again was ready, nabbing the pass and returning it 22 yards.

The Panthers got a field goal off the drive, their first points of the night.

"Their offense still takes a little minute to get going," said Jackson of why they were able to shake Purdy early on, before quickly adding, "but I feel like we should have played better. We had our ops, but we just ain't get the job done."

In the end, only three points off three turnovers was the story of the game, as the offense struggled just a week after setting a franchise record for yards. It meant the defense was on the field for 70 plays and 37:42 minutes, compared to the offense's 43 plays and 22:18 time of possession.

That's no excuse, though, according to Jackson.

"They don't score, they don't win, so we didn't do our part."

To make matters worse, Horn left the game after his second interception with a concussion. He was able to finish the first half, but during halftime, he started to feel nauseous.

"It didn't present as a head injury initially," Canales explained. "And then once he came in for the half, you know, that's when it started to really materialize. So when he came out, and he was feeling nauseous and all that, those are signs that our training staff took and said, 'OK, we got to make sure we do further evaluation on that.'"

He was officially ruled out at the start of the third quarter. Corey Thornton came on in his place, then left himself with a ankle injury on the first defensive drive of the half. He was seen on crutches after the game.

From there, Chau Smith-Wade was moved to the outside, before Akayleb Evans came in to help.

As defensive passing game coordinator, Jonathan Cooley walked through the locker room after the game, he stopped at Smith-Wade's locker, dapping up his second-year defensive back and offering thanks for the way he stepped up tonight with four tackles, including one for loss, and playing back outside, something he hadn't done since college.

"It's the next man up mentality, so you know, we got to look out for our guys," said Smith-Wade. "We pride ourselves on being able to have the next guy up, and there's no fall off. So, that's kind of the mindset when it comes to that."

Added Jackson, "We have arguably like one of the best secondaries in the league, (and) not just top guys like Jaycee, but you go down the whole room, we got guys that can play, and it's guys who can play that y'all don't even know that they might get the (opportunity) this week. So I just know, what them guys gonna bring to the table."

After a solid first half and holding water for as long as possible in the second, the game ended on a somewhat sour note when Moehrig and Jauan Jennings got into a scuffle. Moehrig took a shot below the belt on Jennings, something Canales said he would discuss with Moehrig after the game.

"I'll get to the bottom of that," said Canales. "I want to see what exactly happened, and I haven't had a chance to talk to Tre about that yet, as you know, we've just been kind of talking to the team and wrapping up the day, but that'll be a conversation that I'll dig into."

Moehrig alluded to a tension that had been building all game, and "it just kind of manifested (during the game) with stuff after the play, talking crazy," plus a couple of pushes, Moehrig said, that happened throughout the game.

Now, the Panthers will be on a short week, working through the upcoming holiday in preparation to face the top team in the NFC, the nine-win Los Angeles Rams. They could be shorthanded, given the runway needed to return from concussion protocol. That's the league, though, said safety Nick Scott, and excuses don't matter. The next man has to suit up.

"It's the NFL. Those guys are gonna have to come in, and the expectation is there's no drop off," said Scott. "And then after that, just moving right on. If there are any glaring mistakes that we need to fix from this game, we'll fix them and then see how they apply to the Rams next week.

"But, none of that stuff matters, man. It's the NFL; whoever your opponent is, whatever the record is, it's always next game mentality. Nobody's going to feel sorry for themselves that we got a short week.

"We got a great opponent coming back at our house, we're excited to play, and we're going to give them everything we got."