UNIVERSITY PARK — When Bill O’Brien feels good about a particular play call in favorable field position — it doesn’t matter what the down and distance are — he’s going to keep his offense on the field.

Penn State continuously broke the back of the Northwestern (5-1) defense on Saturday, converting five of six fourth-down plays, two of which were central to impressive scoring drives, to seal Penn State’s 39-28 win at Beaver Stadium.

The Nittany Lions (4-2) finished an 18-play, 82-yard scoring drive when Matt McGloin passed to a tightly covered Allen Robinson who crossed the back of the end zone on fourth and four from the Northwestern six-yard-line. Penn State’s next drive was kept alive in the red zone. Where a conservative approach called for kicking a tying field goal, O’Brien called a pass play on fourth-and-two from the Wildcat 19.

McGloin rolled to his right to avoid pressure and completed a pass to Brandon Moseby-Felder for 13 yards to set up first-and-goal. Four plays later, McGloin outran Northwestern defenders to just inside the pylon to give the Lions a lead they would not relinquish.

Although Penn State had timeouts remaining, O’Brien instead opted to hustle his offense to the line with McGloin snapping the ball quickly on the fourth down attempt.

“You feel pretty good about some plays and you get in a rhythm calling the plays,” O’Brien said. “You’ve been with this No. 11 kid for nine months now and you know the plays that he likes. You feel good about the rhythm he’s in, so you keep it going.”

While the play was intended to be a pass, O’Brien said McGloin always has the option to scramble in a short-yardage situation.

It’s McGloin’s quick mastery of O’Brien’s offense and comfort level with the no-huddle approach that make it an easy decision for O’Brien to go for it on fourth down if the field position is favorable.

“He’s in the film room, he’s in his playbook. He’s controlling the offense at practice and he takes care of that each day,” Running back Michael Zordich said of McGloin. “He works very hard throughout the week. He knows what he needs to do, what he’s looking for and what he’s got to take care of.”

McGloin, who leads Penn State with five rushing touchdowns on the season, credited strength and conditioning coach Craig Fitzgerald with having the team in peak physical shape before the season even started. The team’s fitness, McGloin said, is a reason why O’Brien feels confident his offense can scratch and claw to get yards on fourth-down tries.

So far this season, Penn State is 13-for-20 on fourth down conversions.

"What we did throughout camp, what we did throughout the summer, what we still do during the week, we’re in better shape than every team we play,” McGloin said. “They get tired over there while we continue to push.”

For McGloin’s protectors, Penn State's offensive linemen, being able to grind out short-yardage gains is a matter of professional pride.

They succeeded on fourth-and-1 from the Northwestern 16 midway through the second quarter, battering their way forward to give McGloin room to pick up two yards. The conversion led to a Sam Ficken field goal that gave Penn State a 10-0 lead.

“You have to dig deep, think what has to get done and that’s get the yardage," Penn State center Matt Stankiewitch said. “You have to focus on that play and that play alone and get low and trust that the other guys on your offensive line are going to get low, too, and push the defense back.”

O’Brien said after the game he likely will follow standard procedure and not go for fourth down conversions in his own territory. But he’s liked what he’s seen so far from his offense in fourth-down situations, enough to be ready to go for it if his offense is across midfield and out of kicker Sam Ficken’s range.

“It’s not that hard on a play caller, because your third-down call is like a second-down call,” O’Brien said. “When you know you’re going to go for it, it’s not like all of a sudden you say, ‘We’re going to go for it.’ It’s a thought-out deal and hopefully we continue to execute on fourth down.”