NFL

No defense for Giants’ fourth straight loss

The unofficial end of the Giants 2009 season might have come yesterday on a holding call on usually-reliable Chris Snee followed by a massive breakdown by a defense that earlier flirted with looking as if it had gotten its act together.

The emotional end of the Giants season might have come when Philip Rivers lofted a pass that floated over the beaten cornerback Corey Webster and landed into the hands of Vincent Jackson for a stunning 18-yard touchdown with 21 seconds remaining. It turned a pulsating 20-14 Giants comeback victory into an unfathomable 21-20 loss that prompted players and fans alike to pour out of Giants Stadium wondering what has become of the Giants.

“I thought we fought hard but sometimes you still lose,” center Shaun O’Hara said. “You have to be a man to play this sport, you have to take your lumps.”

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The lumps keep coming for a team that raced to a 5-0 record and is now 5-4. The Giants absolutely will not lose this coming weekend because it’s their bye, giving them an excruciatingly long time to consider how the once mighty have fallen.

“We’re professionals, there’s no quit in us,” defensive end Justin Tuck said. “I don’t think you’ll ever hear the word quit from this team. The effort was there.”

Can the season be saved?

“I’ll let you answer that one,” Tuck said.

PHOTOS: GIANTS LOSE TO CHARGERS

The Giants put everything into this game and came away less than empty. Beforehand, coach Tom Coughlin called it a “one-game season” and Antonio Pierce said it was the Giants’ Super Bowl. Then they engaged in a long and winding struggle with the Chargers (5-3) that included a botched field goal, a 7-7 halftime tie, and a 14-7 deficit heading into the fourth quarter.

A Giants drive that started on their own 21-yard line stalled at the Chargers 19 and Lawrence Tynes hit a 38-yard field goal to make it 14-10. That’s when the game turned, seemingly lifting the Giants out of their losing ways.

At long last, a dominating defense arrived. The Chargers lost 16 yards on their next possession, Eli Manning got the ball back on the San Diego 39-yard line and soon after tossed an 8-yard scoring pass to tight end Kevin Boss. With 8:58 left the Giants had plowed ahead 17-14 and the joint was jumping.

Then, seemingly the hammer. The Giants completely stuffed LaDainian Tomlinson (12-22) and kept Rivers from beating them on big plays. And with 3:14 to go, cornerback Terrell Thomas stepped in front of a Rivers pass intended for Malcom Floyd for an interception that he returned 33 yards, all the way down to the San Diego 4-yard line.

“We should have had the game at that point,” Coughlin said.

Brandon Jacobs rammed the ball to the 1-yard line but the play immediately was called back when Snee, a Pro Bowl guard, failed to make a block on defensive end Luis Castillo and was hit with a 10-yard holding penalty, pushing the Giants back to the 14-yard line.

“It was called and it probably was a good call,” a downcast Snee said. “We punch it in there, we’re up by 10. Game over. Obviously that was an awful play on my part, something I’m going to have to deal with the whole bye week.”

The penalty ruined the possession as the Giants went conservative and settled for Tynes’ 22-yard field goal and a 20-14 lead with 2:07 left.

“You can’t leave that team in the game,” said Manning, who was sharp all night but often had to scramble for his life. “You can’t leave an opening for them. When you have a chance to end it you have to end it.”

Instead, Rivers and the Chargers ended it with a remarkable eight-play, 80-yard drive, as besieged coordinator Bill Sheridan’s defense stopped pressuring.

“I didn’t have anyone near me on eight or nine plays,” Rivers said.

The back-breaker was a 21-yard catch-and-run by Darren Sproles, who ran away from linebacker Michael Boley, followed by an exquisite double-move from Jackson to lose Webster — who didn’t appear to get any help from safety Michael Johnson — for the clincher.

“It would probably be better if we played next week, to be honest with you,” Coughlin said. “We will have to deal with this.”

paul.schwartz@nypost.com