East Rutherford, N.J. ? The Carolina Panthers’ defense played like coach John Fox was in the New York huddle, spying on his former team.

The Giants had no such insight into the Panthers, allowing Steve Smith and DeShaun Foster to beat them at their own game in their own place.

Fox had Carolina prepared for everything New York attempted, rattling Eli Manning into four turnovers, and Smith scored two touchdowns to lead the Panthers to a lopsided 23-0 victory against the Giants in the first round of the NFC playoffs on Sunday.

“We challenged ourselves this week to know the Giants better than they knew themselves,” said Carolina defensive tackle Brentson Buckner.

It was New York’s first playoff shutout in 20 years – and not much of a stretch for the Panthers (12-5) under Fox, who spent five seasons as New York’s defensive coordinator before taking over in Carolina in 2002.

“It was strange – they were in our huddle a little bit,” said running back Tiki Barber, who was held to a season-low 41 yards. “They kind of had us dissected and figured out, and we couldn’t get anything going consistently.”

Not on offense, not on defense and not on special teams. Manning had his worst game of the season, the defense couldn’t find a way to slow Smith or Foster, and the Giants muffed a punt while becoming the first home playoff team to be shut out since 1980, when the Los Angeles Rams blanked Tampa Bay.

The Panthers played nearly as well as they did in their Super Bowl season two years ago and advanced to Chicago (12-4) for the divisional playoffs. The Bears won the only meeting this season, 13-3, in November.

“Everybody may say we’re a Super Bowl team – we’re not,” Smith cautioned. “All we are is a one-win playoff team.”

Carolina did it with a stout defense and a strong running game – the same principles the Giants used this season to win their first divisional title in five years.

DeShaun Foster ran for 151 yards by going straight at the Giants’ depleted linebacker corps, kick-starting a running game that has been spotty all year.

But the play-making is usually reserved for Smith, and he didn’t disappoint with 10 catches for 84 yards. He scored once on a 22-yard catch from Jake Delhomme, then ran a reverse in from 12 yards for a second score.

“In my opinion, he should have been in the MVP voting with his regular-season performance,” Fox said. “I think he just proved his value to us today.”

So did the defense, a staple of Fox’s team.

Carolina intercepted Manning three times, then forced him to fumble late in the game in front of a nearly empty Giants Stadium. Plaxico Burress was shut out the entire game, and the Giants managed just 109 yards total offense.

“I didn’t play well, and I made too many mistakes for us to win today,” said Manning, who finished 10-for-18 for 113 yards.

His struggles had a lot to do with the Panthers, who were insulted earlier in the week when Osi Umenyiora said Carolina had the second-best defensive ends in the NFL. The shot at Julius Peppers and Mike Rucker stung, and the entire unit responded.

Although Umenyiora and Michael Strahan combined for three sacks of Delhomme, Peppers, Rucker and the rest of the Panthers are the ones still playing.

“We were always overlooked. We don’t know why that is,” said safety Marlon McCree, who had two interceptions.

Carolina forced five turnovers in all and kept New York’s offense off the field. It allowed the Panthers to keep the ball a whopping 42:45.

“I believe we still have a lot to be proud of,” Barber said. “We have no reason to hang our heads even though we showed the playoffs weren’t what we were ready for.”

Not on Sunday they weren’t.

The New York crowd, so rowdy at kickoff, booed the Giants off the field after a frustrating first half. It continued most of the second half, until the crowd gave a sarcastic cheer after New York finally managed a first down – one of just nine in the game.

New York unraveled in the second half.

Ken Lucas intercepted Manning on the first play of New York’s second series, setting up Smith’s TD run one play later. And Manning was picked off again on the next series when McCree took a ball intended for Jeremy Shockey at the Carolina 17. It ended the last real scoring threat New York mustered and shattered Manning’s already shaky confidence.