SAN FRANCISCO -- San Francisco quarterback Colin Kaepernick came to the line of scrimmage on fourth-and-1 from the Carolina Panthers' 2-yard line with just more than six minutes left in the first half on Sunday. He barked out signals, giving the appearance, at least, that he was changing the play in an effort to get the Panthers to jump offsides.

They didn't bite.

The 49ers took a delay of game penalty, then settled for a field goal and 9-0 lead.

"That showed this team respect," Carolina linebacker Thomas Davis said.

The Panthers went on to win 10-9, but that moment stands out among a game of big moments for the Carolina defense. It stands out because the 49ers, who already had been stuffed for 1-yard losses on two third-and-1 runs by Frank Gore, admitted they couldn't gain a yard that could have led to a touchdown and changed the entire outcome.

Mike Mitchell and the Panthers sacked Colin Kaepernick six times. Kelley L Cox/USA TODAY Sports

It was even bigger when you consider on the play before the Panthers forced and recovered a fumble by tight end Vernon Davis that everyone at Candlestick Park except the officials saw as a turnover.

The officials ruled it an incomplete pass.

The Panthers didn't let that detour or detract them, either.

"I've played on defenses that had good games," said Thomas Davis, who has been with the Panthers since 2005. "But I haven't been on any that's played the way we're playing since I've been here."

And none that played better than on Sunday.

"Everybody brought their 'A' game, and we needed it," defensive end Charles Johnson said.

Carolina came into the game ranked third in the NFL in total defense and second against the run. It has a chance to move up after holding the 49ers to 151 total yards -- 45 in the second half.

The recipe was simple. It's the same one the Panthers (6-3) have been using all season, and a reason they should be in most games if they continue to do it effectively.

Stop the run. Hit the quarterback. Take the ball away.

"That's what we do," safety Mike Mitchell said. "That's our game plan every week."

The Panthers held a San Francisco team ranked No. 1 in the NFL with 153 yards rushing yards per game to 105 -- 25 in the second half. They sacked Kaepernick a season-high six times.

And on San Francisco's last play they intercepted a Kaepernick pass to win their fifth straight game, sixth in their past seven.

The simplicity of the defense is what makes it so impressive. The Panthers don't use a lot of blitzes and exotic formations. They come straight at you with a seven-man front.

Four of the sacks came when rushing four or fewer defenders.

"Nothing fancy," defensive coordinator Sean McDermott said.

The biggest part of McDermott's game plan against San Francisco was to keep Kaepernick in a lot of third-and-long situations. They were successful, and as a result the 49ers were 2-for-13 on third down.

That's 15 percent if you're doing the math.

Kaepernick was 0-for-6 on throws of more than 10 yards, the first time he's failed to complete a deep pass with multiple attempts for the first time in his career.

Kaepernick also was ineffective running. For the first time this season he was held without an official scramble, and he was 0-for-4 with two sacks when he did escape the pocket.

In other words, the Carolina defense was suffocating.

"I would say we out-physicaled them," coach Ron Rivera said. "That is about as tough as any football game gets."

The Panthers have been playing this kind of defense all season. They held Seattle, considered by many the best team in the NFC outside of San Francisco, to 12 points in the opener.

But this game will open a lot of eyes.

It opened San Francisco's eyes on fourth-and-1 from the 2.

"We say it every week," defensive end Greg Hardy said. "I know the words. We dominate. We take what we want. We do what we want. That's because we work hard."