STATE COLLEGE, Pa. -- With his team a little stunned after giving up a 75-yard punt return for a touchdown, Penn State coach Bill O'Brien walked up and down the sideline giving players a pep talk.

After everything they've been through over the past year, these Nittany Lions weren't going to be denied, even after trailing by 11 going into the fourth quarter.

Quarterback Matt McGloin had the go-ahead score on a 5-yard touchdown run with 2:37 left, one of three fourth-quarter scores for Penn State, and the Nittany Lions stormed past No. 24 Northwestern 39-28 on Saturday.

"Our staff and myself, we tried to talk to the players and get them going," O'Brien said. "We felt like we could move the ball."

And how.

The Nittany Lions (4-2, 2-0 Big Ten) scored three times in the final 9:49, starting with McGloin's 6-yard touchdown pass to Allen Robinson on fourth down as the receiver dragged along the back line of the end zone. Michael Zordich had a 2-point conversion run to get Penn State within 28-25 before McGloin's scramble for a score sent the homecoming weekend crowd into a frenzy.