Iowa State's postseason hopes took a big hit over the weekend after top running back Shontrelle Johnson was severely injured in practice.

Coach Paul Rhoads said Johnson suffered an undisclosed knee injury during a noncontact drill in bowl practice Saturday and will have surgery next month.

"He planted, and you know how violently he plants," Rhoads said. "Something gave."

The Cyclones will use tailback James White against Tulsa in the Liberty Bowl on New Year's Eve.

This is the second consecutive bowl Johnson has missed. Last year, he missed the Pinstripe Bowl while recovering from a serious neck injury. Rhoads said dealing with that injury will help him through this one.

"I think what he's gone through already with the neck has helped his mindset," Rhoads said. "He knows what he's got in front of him as far as rehab, and he'll do a great job with it."

Johnson, who led all Iowa State rushers with 504 yards this season, is the only Cyclone running back to have a 100-yard rushing game this season. He rushed for 120 yards and a touchdown in a 38-23 season-opening win against Tulsa. Johnson would have given the Cyclones an edge in the rematch in a couple weeks.

White, who rushed for 469 yards, has missed practice after taking a hit to the head last week, should be available after he gets over his concussion-like symptoms.

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