Lawrence Tynes kicked a 31-yard field goal after 7:54 of over-time to give the Giants a 20-17 triumph over the San Francisco 49ers in the National Conference final and a berth in Super Bowl 46 on February 5 at Indianapolis.
"It's amazing," Tynes said. "I had dreams about this last night. I was so nervous before this game. I knew I was going to have to make a big kick."
At New England, the Patriots overcame three turnovers and a sub-par performance from quarterback Tom Brady to edge the Baltimore Ravens 23-20 in the American Conference final and advance to their seventh Super Bowl.
"We're going to try to go out and kick some butt in a couple of weeks," said Brady.
Brady scored the winning points on a 1-yard run with 11:29 remaining but the outcome was not settled until Baltimore kicker Billy Cundiff missed wide left on a 32-yard field goal attempt with 11 seconds remaining.
"In the NFL, you have to make big plays in pressure situations and he missed," Patriots coach Bill Belichick said.
Super Bowl 46 will be a rematch of the 2008 title game, in which the Giants edged the Patriots 17-14 to deny New England an unbeaten run to the crown, and a regular-season game last November that was won by the Giants 24-20.
The Patriots have not lost since falling to the Giants, winning 10 games in a row.
"They are a great team," Giants quarterback Eli Manning said. "We just have to go to Indy and play our best football."
New York lost four in a row after beating New England then won three of their last four games just to seize the last vacant playoff berth, then beat Atlanta and upset Green Bay and the 49ers.
The Giants are 3-1 all-time in Super Bowls, having won in 1987 and 1991 as well as 2008 while losing to Baltimore in 2001.
New England has won the Super Bowl three times, all under Brady's direction, in 2002, 2004 and 2005. The Patriots lost the championship spectacle in 1986 and 1997 as well as 2008.
The Giants had the benefit of two botched punt returns by San Francisco's Kyle Williams in taking the triumph.
"It was just a horrible situation," Williams said. "You hate to be the last guy to have the ball and give it up that way."
New York's Jacquian Williams knocked loose a fumble from the 49ers' Williams and the Giants' Devin Thomas recovered at the 49ers' 24-yard line, setting the stage for Tynes' winning kick.
"Just a great play at the end of the game to give us a chance to win," said Giants coach Tom Coughlin. "Eli just hung in there and made the plays we needed, displaying the kind of leadership he has shown all season long."
Another turning point came when New York punted but regained possession of the ball after it bounced off the left knee of San Francisco's Williams and was recovered by the Giants, setting up Manning's 17-yard touchdown touchdown pass to Mario Manningham, putting the Giants back on top at 17-14 with 8:34 to play.
"Just a great effort," Manning said. "We hit a couple of big plays and that was the game. I kept telling myself to be patient, not to force anything. We got some turnovers and used that to hurt them. Our defense was outstanding."
The 49ers, who had two touchdown passes from Alex Smith to Vernon Davis, forced over-time on a 25-yard David Akers field goal with 5:39 in regulation.
"This will take a while to get over," 49ers coach Jim Harbaugh said. "A man can be destroyed but he can't be defeated as long as he knows there's hope."
At New England, Brady, who will match John Elway with a record five career Super Bowl starts, improved to 10-2 in home playoff games and 5-1 in conference finals over his 11 seasons.
But he was only 22-of-36 for 239 yards two inteceptions on Sunday.
"I sucked pretty bad today but our defense saved us," Brady said.
Brady dived over his blockers on a fourth-down play inches from the goal line for a touchdown that gave the Patriots a 23-20 lead with 11:29 remaining.
"It was a big night for us," said Vince Wilfork, who made six tackles. "We knew we had to come out and play some good football."
The Patriots took over with 2:45 remaining but could not run out the clock, setting the stage for Baltimore's final drive, which ended in heartbreak after an end-zone pass drop by Lee Evans and Cundiff's final miss.
"The most disappointing part of all this is that I feel personally that I let everybody down," Evans said. "It's on my shoulders."