Dallas (8-5) led 13-3 midway through the fourth quarter and looked well on its way to securing its fourth consecutive victory before the Steelers pulled the frozen Heinz Field grass out from under the Cowboys.
Moments after Cowboys stopped the Steelers' Gary Russell on fourth-and-goal from the 1, Dallas was forced to punt. Santonio Holmes caught the short kick on a bounce at the Pittsburgh 40 and returned it to the Dallas 25 to set up a 41-yard Jeff Reed field goal. Now down 13-6 with 7:15 to play, Reed attempted to angle his kickoff toward the right sideline. But the ball got caught in the swirling Heinz Field and landed out of bounds resulting in a delay of game penalty that gave Dallas the ball at its own 40.
The Cowboys went three-and-out, but punter Paul Paulescu's kick traveled just 23 yards, giving the ball back to Pittsburgh at its own 33.
Ben Roethlisberger, who was 17-of-33 for 204 yards and a touchdown despite being sacked five times, completed three passes to Nate Washington for 51 yards and scrambled twice for another 10 to put the ball at the Dallas 6 with 2:10 left in the game.
Taking over at their own 15 with all three timeouts remaining following the kickoff, the Cowboys attempted a draw on first down that gained just two yards. Pittsburgh called a timeout, hoping to get the ball back.
On the next play, Townsend picked off Tony Romo – Romo's third interception – and returned it 26 yards for a touchdown.
Dallas still had a chance to tie the game after getting the ball back with 1:40 remaining, but after throwing a 10-yard completion, Romo threw incomplete on four consecutive plays.
The furious rally overshadowed what had been a sloppily-played game in the sub-freezing weather as the two teams staggered to a 3-3 halftime score that featured as many turnovers as points.
But Dallas scored on both of its third quarter possessions on a 12-yard TD pass from Romo to Terell Owens and a 33-yard Nick Folk field goal to take a 13-3 lead. The Steelers had allowed nine third-quarter points this season before surrendering 10 to the Cowboys.