But turning the ball over wasn't the biggest obstacle for the Ravens' offense. It was getting the ball into the end zone.
They had first-and-goal from the Dallas 8 on their first trip inside the 20. The Ravens, though, could move the ball only 1 yard (a scramble by Flacco and a run by McClain resulted a gain of 1 total yard before an incompletion by Flacco).
The Ravens' first series in the second quarter led to first-and-goal at the Dallas 5. This time, the Ravens never moved the ball forward.
On first down, McClain was stuffed at the line despite the Cowboys having only 10 players on the field. On second down, Flacco made a nice pass, but it nearly got picked off because rookie wide receiver Marcus Smith (who was filling in for the injured Mason) didn't keep running to his right. On third down, Dallas linebacker Kevin Burnett came up the middle unblocked to sack Flacco because McGahee didn't pick him up.
That marked the sixth straight time the Ravens failed to score a touchdown in the red zone.
The result: Two red-zone trips led to two field goals by Matt Stover (from 26 and 29 yards) to close the Cowboys' lead to 7-6.
The Ravens took their first lead at the end of the first half when McGahee re-emerged. With 27 seconds left in the second quarter, he gained 21 yards on a catch underneath and ran for 13 yards (his longest run in nine games) to put the Ravens into field-goal range.
Stover's third field goal of the half (a 37-yarder) allowed the Ravens to go into halftime with a 9-7 advantage. In the Cowboys' last first half at Texas Stadium, they were booed off the field.
Asked how the Ravens battled the emotional atmosphere - the Cowboys paraded out stars Emmitt Smith, Michael Irvin and Tony Dorsett before the game as cameras flashed - Harbaugh said: "I think our team was excited about it and fed off it. They were looking forward to coming in here and putting this place to bed. I think we did it in a fitting way for the Ravens."