This was the biggest win for Iowa in years, its first against a top-five team since 1990. The Hawkeyes suffered through two seasons of mediocrity after finishing No. 8 in the country three years in a row.

The Hawkeyes had lost four games this season by a total of 12 points -- and they got beat last week by Illinois on a 46-yard field goal with 24 seconds left.

"We knew we had enough to win," Iowa linebacker A.J. Edds. "But there weren't a whole lot of people on the outside that thought we were the kind of team we know we are. We showed that today."

Clark was 9-of-23 for 86 yards and Derrick Williams and Evan Royster each ran for touchdowns to lead Penn State (9-1, 5-1), which had to settle for Kevin Kelly's field goals on three different trips inside Iowa's 20.

On a day where the wind chill dipped into the 20s, Penn State held the ball for nearly 36 minutes and ran almost twice as much as they threw it.

It worked for the first three quarters.

Penn State's Tyrell Sales picked off Stanzi on the opening drive of the third quarter, and Kelly's 25-yard field goal put the Nittany Lions ahead 16-7. Iowa's offense finally woke up, reeling off a 73-yard drive that Stanzi capped by finding a wide-open Johnson-Koulianos for a 27-yard touchdown pass to pull the Hawkeyes within 16-14 with 4:43 left in the third.

But Stanzi fumbled away the ball and Iowa's momentum just two minutes later, giving Penn State the ball deep in Iowa territory after botching the snap. The Nittany Lions wasted little time turning Stanzi's mistake into points, as Williams' 9-yard touchdown run put Penn State back up 23-14 heading into the fourth.

Penn State held the ball for an astounding 23:34 and outgained Iowa 203-70 in the first half.

But the Hawkeyes forced a pair of red-zone field goals, keeping Penn State's lead at 13-7.

After falling behind 7-0 early in the first quarter, the Nittany Lions put together scoring drives of 71, 75 and 78 yards -- all powered by the running game.

They had to settle for 24-yard field goal by Kelly on the first one, but Royster ran for a 2-yard score to give Penn State a 10-7 lead early in the second quarter.

Kelly drilled a 31-yarder into the with 55 seconds left in the first half.

The Nittany Lions were shooting for their first 10-0 start since 1994 -- incidentally, the last time Penn State went undefeated but didn't win it all -- but with home games against Indiana and Michigan State left, a Big Ten title is still Penn State's to lose.

"Their balloon still isn't busted," Paterno said. "If we win the next two we'll have an opportunity to go to a big bowl."