No information was available on the extent of the injury. According to Green Bay's official Twitter feed, Pickett will not return:
Ryan Pickett has a calf injury and will not return.— Green Bay Packers (@packers) August 24, 2012
The Packers were leading the Bengals 17-6 at the time of the injury. Pickett, entering his 12th NFL season, is Green Bay's starting left defensive end. He had 33 tackles in 14 games for the Packers last season. He's backed up by Phillip Merling.
Follow this game stream for updates on Pickett's injury as well as updates on the rest of tonight's game.