IOWA CITY, Iowa -- Iowa quarterback Ricky Stanzi was taken to the locker room after suffering a sprained ankle in the Hawkeyes' (No. 4 BCS, No. 8 AP) 17-10 loss to Northwestern.

Head coach Kirk Ferentz said X-rays were negative, but it doesn't look good for him to play next week.

"The bad news is it's a severe sprain," Ferentz said. "My guess is he'll be out of action here the next couple weeks."

"If they've X-rayed it, I've got to think it's fairly serious. ... It takes time for those things to get right. ... Right now we have to take the approach that he won't go, and if he does, that's a bonus."

Stanzi was drilled by Corey Wootton in the end zone, and his fumble was recovered by Marshall Thomas for a touchdown that brought Northwestern within 10-7.

Stanzi was limping as he was helped off the field. He was replaced by redshirt freshman James Vandenberg, whose first pass was intercepted.

Later in the game, Northwestern quarterback Dan Persa suffered a hand injury and and never returned.

Stanzi was 4 of 9 for 134 yards with a touchdown and an interception before leaving the game. He came into the game 17-3 as the starter since taking over the middle of last season.

ESPN.com Big Ten blogger Adam Rittenberg contributed to this report.