Best: Beginning of some dark days for Giants?

For a team that had just lost horrifically at home to a wounded rival, the Giants were surprisingly matter of fact in their locker room - more disappointed than disgusted, more determined than dispirited.

"We're not going to lose our confidence,'' said safety Antrel Rolle, who last month declared the Giants the best team in the NFL. "We're not going to lose our swagger.''

Fair enough. The Giants had won five in a row before yesterday's 33-20 debacle against the Cowboys, so they were due for a stumble in the can't-win-'em-all NFL, even against can't-win-often Dallas. But it also is fair for fans to worry, given the magnitude of the flop and Tom Coughlin's history.

The coach is a combined 41-15 in the first halves of his seven regular seasons in blue. Now he is 20-29 in second halves, including last year's late fade. With a crucial game against the Eagles looming, might this be the first step toward another cliff?

It certainly looked that way on a bizarre day that featured a brief power outage at New Meadowlands Stadium and a sustained power surge by the Cowboys in interim coach Jason Garrett's debut.

The lesser concern was the offense. Operating with a makeshift line and without receiver Steve Smith, the Giants did what they have done before, moving the ball with alacrity but ruining it with penalties and turnovers.

That's how you lose despite advantages in first downs (25-15), total yards (480-427) and possession time (37:51-22:09).

"Maybe a few things we've gotten away with in the past you kind of know eventually are going to bite you, and today they definitely bit us,'' said Eli Manning, who threw for 373 yards and two touchdowns but had two red-zone interceptions, one returned 101 yards for a game-turning score.

He also tried to pick up the ball and attempt a desperation pass after a bad center snap when he should have fallen on it, allowing Dallas to recover. "I made a bad decision,'' he said.

That's all fixable. It was what happened on defense that had to spook the team and its fans, especially given what happened to that unit late in 2009.

Jon Kitna, overwhelmed after replacing Tony Romo the last time the teams played, threw for 327 yards on only 13 completions, with five receivers recording plays of at least 27 yards.

It was a shocking meltdown for a widely lauded, mostly injury-free group.

"It is football and we are humans,'' end Justin Tuck said. "Sometimes you play lights out, literally, and sometimes you just don't have it.''

Several players pointed to Felix Jones' 71-yard catch-and- run as an example of the Cowboys making all the right moves. The Giants had a linebacker blitzing one way and Dallas went the other.

Jones' touchdown came after play resumed with one end of the field in dusk because of the outage. Did the Giants literally not see what was coming?

"No, no, no, no, no, the lights didn't affect us at all,'' Rolle said. "If he scored, he was going to score. Lights on, lights off, it didn't matter.''

The Giants promised to return to work Monday with a bright outlook and no dark thoughts of late autumns past. Tuck said the team has learned its lessons and that he was glad for the wakeup call. "I think last year we started making excuses for it,'' he said, "and I can just tell by the conversations that I had in the locker room we will get them next week.''

Fans will be watching and waiting, and trying not to look at the calendar.