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 the Giants attempted, rattling Eli Manning into four turnovers, and Smith scored two touchdowns to lead the Panthers to a lopsided 23-0 win over the Giants in the first round of the NFC playoffs yesterday.

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

Fox still maintains close relationships with everyone from the front office to the cleaning crew, and marked his return to the Meadowlands by staying one step ahead of everything the Giants tried to do.

“It was strange – they were in our huddle a little bit,” Tiki Barber, who was held to a season-low 41 yards, said. “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 for the divisional playoffs. The Bears won the only meeting this season,13-3 in November. 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. It was just his third 100-yard game this season – the other two came against Atlanta, leading to questions if Foster could run on any other team.

“I don’t think they thought we would really run the ball against them, but we established it early,” Foster said. “It was just wide open. I got right to the second level, early. If I can get to the second level, I can make things happen.”

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 12 yards for a second score.

The defense came to play as well. 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. “It was not the way I wanted to come out and play. I look forward to coming back and getting better.”

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.

Carolina forced five turnovers in all and kept the Giants’ 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 yesterday 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.

Carolina used New York mistakes to aid most of its scoring. They jumped out to a 7-0 lead after Justin Tuck was called for illegal contact on a third-down incompletion. It kept the Panthers’ drive going, and they moved the ball efficiently with a mix of runs by Foster and Nick Goings to put the Giants on their heels. Smith then shed his double coverage and easily beat Terrell Buckley into the end zone for a 22-yard touchdown.

Then, right before halftime, the Giants muffed a punt when the ball hit Gibril Wilson’s knee and Carolina pounced on it. Four plays later, John Kasay kicked a 31-yard field goal for a 10-0 lead the Panthers took into the break.

The Giants unraveled in the second half. Ken Lucas intercepted Manning on the first play of New York’s second series, setting up Smith’s touchdown run one play later. 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.