49ers ready to get smash-mouth on Giants

SAN FRANCISCO — This is what makes the 49ers so challenging: They don’t just want to beat you physically, they want to punish you. In their own words, they want cruelty to rule the day on defense.

That is what the Giants will be up against Sunday at crazy Candlestick Park — a defense that goes for the jugular every play. The Giants’ defense is rolling, too, so this should be a classic NFC Championship.

“You want to play in Candlestick,’’ 49ers guard Adam Snyder said after his team’s 36-32 Divisional win over the Saints on Saturday on why he was rooting for the Giants to beat Green Bay. “We have the best fans in the NFL. That’s the loudest I’ve ever heard them.’’

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Safety Donte Whitner knocked Saints running back Pierre Thomas out cold 2 yards from the end zone on the first series Saturday, setting the tone with his hellacious helmet-to-helmet hit, getting those fans going.

Thomas fumbled and the 49ers recovered the first of five turnovers in a win that sent them to the NFC title game the first time in 14 seasons.

Whitner was asked about the mindset behind such a hit.

“The offensive guys see that and they don’t want to be hit the rest of the game,” he said.

Did Whitner feel the collision?

“I didn’t feel anything. My adrenaline was running through me.’’

Whitner ran through Thomas. That is the 49ers’ game plan under first-year NFL coach Jim Harbaugh. That mindset, and offensive magic from quarterback Alex Smith and tight end Vernon Davis, carried the 49ers on Saturday.

On Nov. 13, San Francisco beat the Giants 27-20 at Candlestick, but this is a much different Giants team. The 49ers will attempt to hammer Eli Manning just as they did Drew Brees.

“They’re a big, tough, physical team that comes up and hits you,’’ Brees said. “They thrive on that.

“They’re revved up and you just know it’s going to be an all-day sucker.”

Brees was sacked three times and hit another 11 times. The 49ers play for the kill shot. They created 38 turnovers during the regular season and only gave the ball away 10 times.

They play in a stadium stuck in the 1960s and play the game with a defense reminiscent of that era. They punish you.

“Nobody had us in this position in the beginning of the year,’’ Whitner said. “It feels great to be one game away from the Super Bowl. We prepare so hard mentally throughout the week. Guys take their work home, they come in early, they get extra lifts. They do everything that we have to do to be prepared when we step on the football field. That’s why some of the luck has turned our way now. We want to go out and win this game and be in the Super Bowl, that’s all there is to it.’’

The 49ers are looking to make more history Sunday with big hits and big plays. The Giants are looking to do the same. Bring it on.

kevin.kernan@nypost.com