Northwestern (2-0) didn't score a touchdown in the first three quarters but managed 17 points in the fourth to come away with another dramatic win after beating Syracuse 42-41 in the opener.
The Wildcats finally found the end zone when Mark ran it in from the 7 to give Northwestern a short-lived 13-10 lead with 9:28 left in the game. Vanderbilt's Zac Stacy then turned a short swing pass into a 55-yard gain that put the ball on the 14, but instead of a touchdown, the Commodores had to settle for a tying 26-yard field goal by Carey Spear.
Northwestern caught a break on the next drive when Trevor Siemian's 34-yard pass to Rashad Lawrence along the left sideline was ruled a completion even though he fumbled the ball as he went out of bounds. The call was upheld after a review, putting the ball on the Vanderbilt 22, and Jeff Budzien kicked an 18-yarder with 2:01 remaining to break the tie.
Scott then forced a fumble when he sacked Jordan Rodgers on Vanderbilt's next play from scrimmage, and Dean Lowry recovered the ball. That led to a 29-yard TD run by Kain Colter, sending Vanderbilt (0-2) to another difficult loss.
Mark came up big again after tying a personal best with 281 all-purpose yards in the opener.
Colter looked fine physically Saturday night after pulling himself out of the game in the closing minutes of last weeks contest because his bruised ribs made it too painful to throw. He managed to throw for 42 yards and run for 66 against Vanderbilt.
Siemian completed 10 of 16 passes for 91 yards Saturday after throwing the winning TD last week.
Suffering two losses to begin this season isn't the start Vanderbilt envisioned after going 6-7 in 2011 and playing in only the program's fifth bowl game ever in coach James Franklin's debut season. The Commodores get a breather next week against Presbyterian before a gauntlet the following few weeks which begins with trips to Georgia and Missouri before home games against Florida and Auburn.