EVANSTON, Ill. -- In the rare event when running back Saquon Barkley can't get untracked, Penn State has other options.

Trace McSorley completed 25 of 34 passes -- including a school record 15 in a row -- for 245 yards and a touchdown, also running for a score, as No. 4 Penn State dominated Northwestern 31-7 Saturday, spoiling the Wildcats' homecoming.

"It's pretty cool," McSorley said of the record, previously held by Kerry Collins. "I had no idea about that."

Northwestern focused on stopping the Heisman Trophy candidate Barkley, who had minus-1 yard rushing at halftime. But he finished with 16 carries for 75 yards and two touchdowns, including a 53-yard touchdown run that gave the Nittany Lions (6-0, 3-0 Big Ten) a 24-0 lead late in the third quarter.

McSorley said the performance demonstrates Penn State's ability to win in a multitude of fashions, particularly when teams key in heavily on Barkley, who entered the game leading the Big Ten in rushing yards and all-purpose yards.

"I think that's definitely something that, as a team, we continue to learn more and more each week," McSorley said.

McSorley's only touchdown pass came on a 10-yard toss to backup quarterback Tommy Stevens with 12:04 remaining in the first half, giving Penn State a 10-0 lead.

Stevens took over quarterback duties for McSorley after the game was out of reach, completing 4 of 7 pass attempts for 41 yards and running three times for 17 yards.

Northwestern (2-3, 0-2) crumpled in the second half at the hands of Penn State's stifling defense, which entered the game with the conference's third-most efficient pass defense. The Wildcats gained 99 yards in the second half, 23 of which came on a late touchdown drive.

"I'm disappointed with our performance today," Northwestern coach Pat Fitzgerald said. "We had, I think, ample opportunities in the first half to seize the moment and just couldn't get that done collectively as a team. Against an outstanding football team, you can't do that. You can't leave opportunities out there."

Wildcats quarterback Clayton Thorson finished 19 of 36 for 142 yards and two interceptions.

In the first quarter, Penn State cornerback Amani Oruwariye intercepted Thorson at the Nittany Lions' 10-yard line, ending a 12-play drive that lasted 5:07.

"It was a big momentum play," said Oruwariye, who leads Penn State with three interceptions. "We're just playing with a lot of confidence. We study a lot of film, so it makes the game a lot easier. I was telling the other guys, 'A team with confidence is dangerous.' "

The Nittany Lions initially struggled to run the ball, amassing minus-2 rushing yards in the first half. Despite its 10-0 halftime lead, Penn State managed only 146 yards of offense to Northwestern's 166.

"When you're playing at a pretty high level -- I would say we're playing winning football in all three phases -- when you're able to do that, there could be a week where one of the units isn't playing as well as it should, and you still have a chance to overcome it because you've got two of the three that are playing well," Penn State coach James Franklin said. "It creates a little bit of wiggle room for you."

After extending the lead to 17-0 on a 1-yard touchdown run with 9:33 remaining in the third quarter, Barkley broke free for his long run, capping a four-play, 76-yard drive that lasted 1:06.

McSorley said the offense never panicked and was committed to improving the run game in the second half.

"That's what we were saying, 'Just keep grinding it out.' Saquon's going to end up popping one off at some point. It's not a matter of if, it's a matter of when," McSorley said.

Northwestern's lone score was a 1-yard touchdown run by backup quarterback Matt Alviti with 1:46 remaining, following a 25-yard reception by Jace James. Alviti replaced Thorson late in the fourth quarter, and finished 4 of 7 for 54 yards to go with three carries for 20 yards.

"Now we've got to figure it out and we've got to come back swinging," Fitzgerald said. "We put our own backs against the wall and we're the only ones that can fix it."

NOTES: Penn State has outscored its opponents 76-0 in the first quarter. ... Northwestern has not surrendered an opening-drive score this season. ... Penn State backup QB Tommy Stevens has a touchdown rush, a touchdown pass and two touchdown receptions this season. ... Northwestern QB Clayton Thorson is now the fifth-leading passer in school history, eclipsing Zak Kustok's mark of 5,822 yards. Thorson needs 24 yards to pass Trevor Siemian for fourth all time. ... Penn State QB Trace McSorley has thrown a touchdown pass in 21 consecutive games. ... Northwestern LB Paddy Fisher was ejected in the third quarter for a targeting hit on McSorley. Fisher entered the game as the Wildcats' leading tackler, and finished with six combined tackles.