Carr intercepted a pass from Roethlisberger on the second play of overtime and returned it 36 yards to the 1, setting up Dan Bailey's 21-yard field goal that gave the Cowboys a 27-24 win over the Steelers on Sunday.
Bailey's kick—1:24 into OT—won a game for the second straight week since Dallas practice squad linebacker Jerry Brown was killed in a one-car accident that led to manslaughter charges against teammate Josh Brent.
The Cowboys (8-6) have won five of six and pulled even with the New York Giants and Washington atop the NFC East with two games remaining.
Carr, who said he was anticipating Roethlisberger's throw to Mike Wallace because Steelers offensive coordinator Todd Haley was his coach in Kansas City, made a diving catch and jumped up along the Pittsburgh sideline. Legions of black-and-gold clad fans on that side of the stadium watched in silence as Carr came within inches of ending the game himself.
"That was like a buzzer-beater," Dallas defensive end Marcus Spears said. "That guy studies the game and understands it. There is no doubt in my mind that he knew that was coming."
The winning kick came after Tony Romo, who broke the 25,000-yard passing milestone earlier in the game, took a knee to put Bailey in better position. Bailey beat Cincinnati 20-19 last week with a 40-yarder as time expired, just a day after the accident that killed Brown.
Brown's death came a week after Kansas City Chiefs linebacker Jovan Belcher, Carr's former teammate, fatally shot his girlfriend before driving to Arrowhead Stadium and committing suicide in front of his coach and general manager.
The Cowboys draped Brown's No. 53 jersey over the bench—just as they did in Cincinnati a week ago—and had a helmet decal with his number. Brent, accused of driving drunk in the fatal accident, watched from the sideline.
"We have a lot of heavy hearts right now," Carr said. "Fifty-three was on the sideline today, so after the interception, that's where the game ball went."
The Steelers (7-7) lost for the fourth time in five games and trail AFC North rival Cincinnati by a game for the second wild card spot. They host the Bengals next week.
Roethlisberger is 0-2 since returning from a three-game absence with shoulder and rib injuries, and he lost to the Cowboys for the first time in three starts. It was Pittsburgh's first trip to Cowboys Stadium since losing to Green Bay in the Super Bowl two years ago.
"There won't be any quit from us, especially from me," Roethlisberger said. "This one is going to sting real bad. It will hopefully make me and make us better."
The defining play came from a Dallas defense playing without six injured starters, the latest being Carr's playing partner on the other side, first-round pick Morris Claiborne. The rookie was sidelined after sustaining a concussion against the Bengals.
"I really can't explain it. It's something destined about this team," defensive end Jason Hatcher said. "You look back there and you don't know nobody back there behind you."
The score was tied 24-all in the final two minutes of regulation. Pittsburgh quickly moved to its 46 after a completion by Roethlisberger and a roughing-the-passer penalty against DeMarcus Ware.
But Sean Lissemore and Anthony Spencer sacked Roethlisberger on consecutive plays to give the Cowboys the ball back.
"Everyone has seen Ben do that in the fourth quarter multiple times," Spears said. "We knew we had to go back there and affect him in the pocket and at least try to get in his way. Fortunately, those turned into some sacks for us."
The Cowboys couldn't do anything in the final minute. Their drive stalled at the Steelers' 43, and Bailey lined up for a 61-yard field goal attempt with 32 seconds left. But Dallas called timeout and punted instead. Roethlisberger took a knee, sending the game to overtime.
Roethlisberger was sacked four times and finished 24 of 40 for 339 yards with two touchdowns and an interception.
"We're still in the same situation we started in before we came," said Wallace, who had 95 yards receiving, including a 60-yarder to set up a touchdown. "We know we win these last two games, we're still in the tournament."
Earlier in the fourth quarter, Pittsburgh was driving for a go-ahead score when Ware and Spencer sacked Roethlisberger at the Dallas 40, forcing a punt with three minutes left. The Cowboys opted to punt at the two-minute warning after a third-down pass to Dwayne Harris was less than a yard short of the first down.
Roethlisberger put the Steelers ahead 24-17 with a 7-yard scoring pass to Antonio Brown, and Brown was about to put Pittsburgh in control with a long punt return.
But Brown fumbled when Victor Butler reached out and knocked the ball loose at the end of a 22-yard return. DeMarco Murray, who had 81 yards on 14 carries, then scored on a 3-yard run.
"There was about five or six guys, all in black and yellow," Butler said. "And I see the punter and me and the long snapper and I figure I am probably the best tackler out of the three. It was time to make a play."
Dez Bryant extended his touchdown streak to six games while playing with a broken left index finger, a 24-yard score that put Romo over 25,000 yards for his career and gave Dallas a 10-0 lead.
Roethlisberger pulled the Steelers even before halftime. He stepped away from pressure and used a couple of pump fakes to keep pass rushers away before finding Heath Miller wide open along the sideline on a 30-yard score.
NOTES: The first Dallas touchdown was the first scoring connection from Romo to TE Jason Witten this season. ... Steelers CB DeMarcus Van Dyke injured a shoulder on Pittsburgh's first punt less than two minutes into the game and didn't return. ... Dallas rookie TE James Hanna had two career catches for two key grabs on the Cowboys' first touchdown drive. ... The Grambling State band spelled out "JB" in honor of Brown at halftime. ... The loss snapped Pittsburgh's three-game winning streak in overtime. Dallas is 2-0 in OT at Cowboys Stadium after beating Cleveland last month. ... Attendance was 95,595, a season high at Cowboys Stadium.