IOWA CITY, Iowa (AP) - It was happening like it had so often in the past.
A once-sluggish Iowa team had come to life in the fourth quarter at home under the lights, and another top-five opponent was set to go down.
Trace McSorley, Juwan Johnson and the resilient Nittany Lions flipped the script, scoring on the game's final play to survive a wild Big Ten opener.
Johnson caught a seven-yard TD pass as time expired and fourth-ranked Penn State rallied to stun Iowa 21-19 Saturday night.
Saquon Barkley had 211 yards rushing and 94 yards receiving for the Nittany Lions (4-0, 1-0), who outgained Iowa 579-273 but nearly blew a game that could've been crippling to their postseason hopes.
"Felt like with (Johnson) we had a height advantage and we could slip him through the middle of the field," Penn State coach James Franklin said of the winning play.
Akrum Wadley had a 70-yard TD reception midway through the fourth quarter and a 35-yard touchdown run with 1:42 left to put the Hawkeyes (3-1, 0-1) ahead 19-15.
Penn State went 80 yards on 12 plays and just 1:42 to close out the game, and McSorley found Johnson in a crowded end zone on fourth down.
McSorley finished with 284 yards passing on 48 tries.
Wadley had 80 yards rushing and 75 yards receiving and Nate Stanley threw for 191 yards and two TDs for Iowa.
"It's a tough loss for all of us," Iowa coach Kirk Ferentz said. "You can see first-hand why they were the Big Ten champs last year."
Penn State: Michigan came into Iowa City in a similar spot a year ago and lost 14-13, so the Nittany Lions should be happy they avoided a loss that would've erased their margin of error for the playoffs. Barkley was unstoppable and Penn State's defense was brilliant. But the Nittany Lions didn't do a ton in the passing game until the final drive — when McSorley's final pass was right on the money.
Iowa: The Hawkeyes' defense, led by preseason All-American linebacker Josey Jewell, played its heart out. Wadley then put Iowa in position to make a major statement nationally, but the Nittany Lions simply made one more play than they did. "This game sucks. But you've got to move on," said Jewell, who finished with 16 tackles.
Third-ranked Oklahoma struggled with a winless Baylor on the road, and Iowa is clearly better than the Bears. But it's unclear if Penn State did enough to leapfrog the Sooners — who have a win over Ohio State to their credit.
Penn State faced a 3rd-down-and-6 up just 15-13 midway through the fourth quarter. McSorley threw a swing pass to Barkley, who was pinned to the sideline. But Barkley charged up the field, leapt over a Hawkeyes defender and got the first down — keeping alive a drive that burned the clock. "The big difference in the game was that running back. He's a phenomenal player," Ferentz said. Barkley also caught 12 passes.
Penn State ran 99 plays. Iowa had just 45. ...Stanley has thrown for 12 touchdowns against just one interception in his first four starts. ...Johnson finished with 92 yards on seven catches. ...Penn State gained 29 first downs, while Iowa had just 11.
HE SAID IT
"I cannot imagine there is a better player in all of college football. The guy is special," Franklin said of Barkley.
Penn State hosts Indiana on Saturday.
Iowa plays at Michigan State next weekend.