Bailey's kick -- 1:24 into OT -- won a game for the second consecutive 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 win pulled the Cowboys (8-6) into a three-way tie for first place in the NFC East with the New York Giants and Washington Redskins with two games left in the season. Dallas has won five of its last six.
"Those are the plays you dream about in the backyard, making the game-winning interception or touchdown," Carr said.
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 as Carr ran it back and was stopped inches short of the goal line.
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.
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.
"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.
"Everyone has seen Ben do that in the fourth quarter multiple times," Dallas defensive end Marcus 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."
Dallas, playing with Brent watching from the sideline and Brown's No. 53 jersey draped on their bench and his number on a helmet decal, couldn't do anything in the final minute.
The drive stalled at the Steelers 43, and Bailey lined up for a 61-yard field goal attempt with 32 seconds left. But the Cowboys called timeout and punted instead. Roethlisberger took a knee, sending the game to overtime.
Roethlisberger was sacked four times and finished 24-of-40 passing for 339 yards with two touchdowns and an interception.
"We're still in the same situation we started in before we came," Wallace said, 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.
"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 gave Romo more than 25,000 yards for his career and gave Dallas a 10-0 lead.
Roethlisberger pulled the Steelers even at 10 before halftime. He stepped away from pressure and used a couple of pump fakes to keep pass rushers away before finding tight end Heath Miller wide open along the sideline on a 30-yard score.
"We still have a chance to right our wrongs here with two games left," Miller said. "We're just going to keep chipping away at it."
NOTES: The first Dallas touchdown was the first scoring connection from Romo to 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. ... Cowboys LB Ernie Sims sustained a concussion in the first half and didn't return. ... Attendance was 95,595, a season high at Cowboys Stadium.
Copyright 2012 by The Associated Press