IOWA CITY, Iowa — With quarterback Ricky Stanzi watching from the sideline on crutches, No. 8 Iowa ran out of magic.

Dan Persa threw a touchdown pass and Marshall Thomas recovered a fumble for another score, and Northwestern dealt a crushing blow to Iowa's BCS title hopes with a 17-10 victory Saturday. Stanzi was knocked out of the game with an ankle injury in the second quarter on the play in which Thomas scored the Wildcats' first touchdown to spark the upset.

"Any time you lose your quarterback, that's not good," Iowa coach Kirk Ferentz said.

The Hawkeyes have been living dangerously all season, making a habit of comebacks and close games. Still, they were good enough to be fourth in the latest BCS standings, hoping that a slip by others could land them in the BCS title game. But now that their 13-game winning streak is over, the focus shifts to trying to win the Big Ten and land in the Rose Bowl for the first time since the 1990 season.

Freshman James Vandenberg came in for Stanzi and was just nine of 27 pasing for 82 yards and couldn't lead the Hawkeyes to any points. Ferentz said that while preliminary X-rays on Stanzi's ankle were negative, he'll likely be out a couple weeks. That's not a good sign for the Hawkeyes heading into next week's game at Ohio State.

Northwestern scored twice off turnovers in the second quarter. Thomas' fumble recovery made it 10-7. Then Drake Dunsmore caught a 4-yard TD pass from Persa after another Iowa turnover and the Northwestern defense clamped down.

This was a huge win for Northwestern, which just last week got drilled by Penn State 34-13.

"It's critically important to show the direction to all those recruits throughout the country that, absolutely, Northwestern's for real," coach Pat Fitzgerald said. "You better get on the boat right now because the ship's leaving the shore."