The Steelers were on a roll heading into the game against the Cowboys.
They were up by 21 points with 2:02 left in the third quarter and were up 20-7 heading into halftime.
But then quarterback Ben Roethlisberger hit rookie wide receiver Markus Wheaton for a 28-yard touchdown.
The Steelers never recovered, and it ended up costing them the game.
The Cowboys have the worst record in the NFL at 6-5.
But in the last 10 games against the Steelers, they have only dropped three of the last five.
The next time the two teams meet, the Steelers will get the chance to bounce back from their loss on Sunday.