Now the Dallas quarterback has to figure out how to make the comeback turn into more victories without All-Pro receiver Dez Bryant, who will miss four to six weeks with a broken right foot.
"We'll try to reassess that and figure out where to put guys," Romo said after his 11-yard scoring toss to Witten with 7 seconds left gave the Cowboys a 27-26 win over the Giants. "No one can replace Dez Bryant, but it's my job to help that whole situation."
The Cowboys drove 72 yards in 1:27 after stopping New York at the 1 and forcing Josh Brown's fourth field goal when a touchdown would have sealed the Giants' first victory in an opener against Dallas.
The defending NFC East champion Cowboys are 8-0 against their division rival in openers, and have beaten them five straight times.
The Giants tried to throw on third down from the Dallas 1 with a 23-20 lead, but the Cowboys weren't fooled by the play-action fake. Eli Manning threw the ball away instead of taking a sack, stopping the clock and giving Romo the final 1:34 to try to win.
"It was bad clock management," said Manning, who had 193 yards passing with no touchdowns after throwing for 12 TDs in his previous four games against Dallas. "It was definitely an option to take a sack and run 40 seconds off the clock and give them less time. That's 100 percent on me."
But coach Tom Coughlin took the blame as well.
"The decision to throw the ball on third down was not a good decision," he said. "It should have been a run, whether we scored or not."
On the winning play, Romo picked up ball after a low snap and found Witten — who finished with eight catches for 60 yards and two TDs — shielding defenders at the goal line. The 13-year veteran made the catch, stayed on his feet and left no doubt about getting the ball in the end zone for yet another huge connection between one of the most prolific quarterback-tight end combos in NFL history.
"With what I've experienced here, he's always great in 2-minute, especially him and Witten," Giants cornerback Prince Amukamura said. "You can tell he's very poised and you definitely don't want the ball in his hands in the final two minutes. But whenever that's the case, the defense has to step up."
Romo, who threw for 356 yards with three touchdowns and two interceptions, led two quick touchdown drives in the fourth quarter after McBride's interception set up Rashad Jennings' 1-yard scoring that put the Giants up 23-13 with 8 minutes to go.
Some observations after the Cowboys improved the best season-opening winning percentage in NFL history (.670, 37-18-1):
NO DEZ, SO DUNBAR: Running back Lance Dunbar got the final Dallas drive going with two catches for 40 yards. He finished with team highs of eight catches for 70 yards with Bryant twice leaving the game. The first time was in the first half because of dehydration.
BIG HITS: McBride's interception was the result of safety Brandon Meriweather's jarring hit on Dallas receiver Devin Street knocked the ball into the arms of McBride. The New York cornerback originally was given a touchdown on a 20-yard return, but replayed showed him stepping out at the 1.
In his first meeting with the Cowboys since his astonishing one-handed touchdown catch last season, Giants receiver Odell Beckham Jr. wasn't much of a factor with five catches for 44 yards. Dallas safety J.J. Wilcox hit him hard on a crossing route in the first quarter, knocking the ball out.
10 QUICK POINTS: The Giants converted two Dallas turnovers into 10 points in the final minute of the second quarter. Rodgers-Cromartie picked up a fumble by receiver Cole Beasley just before he hit the ground at the end of a run and ran untouched for a 10-6 lead, cutting from the sideline to the middle of the field to avoid Romo along the way.
On Dallas' next snap, Romo threw behind Witten, who tipped the ball into the arms of linebacker Uani Unga, starting because Jon Beason missed the game with a sprained left knee. The Giants had to settle for Brown's second field goal, from 40 yards.