Gramatica's winning kick went straight through the uprights with plenty of power, more than making up for his wide-right miss from 44 yards to end the Cowboys' opening drive.
The winning score was set up by a 42-yard pass by Tony Romo to Jason Witten and came just over a minute after the Giants had tied the game at 20-all on a 5-yard TD pass from Eli Manning to Plaxico Burress.
Gramatica, who also kicked field goals of 41 and 35 yards, was signed last week after the Cowboys cut Mike Vanderjagt. But being the new guy didn't keep Gramatica from bursting into one of his trademark wild celebrations: The diminutive kicker leaped into the arms of his teammates, while coach Bill Parcells broke into a wide smile on the sidelines as the ball sailed through.
"I've got to thank the Cowboys for giving me a second chance," said Gramatica. "It's been a rough couple of years for me, being out all last year and then not making any teams this year."
It was the fourth straight loss for the Giants (6-6) and the. fourth win in five games for Dallas (8-4) since Romo replaced Drew Bledsoe at quarterback at halftime of a 36-22 loss to New York on Oct. 23. He finished 20-of-34 for 257 yards with two interception.
"Anytime you come up to this place you know it's not going to go smoothly," Romo said. "We made mistakes today. I know I did. You just have to have a chance to do something at the end of the game to win."
There were three scores in the final 3:33.
First Marion Barber II scored on a 1-yard run. Then Eli Manning drove the Giants 63 yards for the tying score on the pass to Burress.
But Romo hit Witten on the first play after the kickoff with a strong throw to take the Cowboys to the Giants 26.
'Boys Take Control in NFC East
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