The Arizona Cardinals' offensive hopes took a big hit when rookie running back Ryan Williams was carted off the field with a right knee injury early in the third quarter during a preseason loss to the Green Bay Packers Friday night.

Cardinals coach Ken Whisenhunt said the team was "pretty certain" Williams ruptured his patellar tendon.

"If it is what we suspect, then, yes, it's a season-ender," Whisenhunt said.

A Packers player appeared to land awkwardly on the right leg of Williams, a second-round pick out of Virginia Tech.

"It's disappointing because we had such high hopes for him this season," Whisenhunt said. "But that's what happens in this game, and we have got to move forward."

Information from The Associated Press was used in this report.