Buccaneers' running back Cadillac Williams will begin the season on the physically unable to perform list, according to ESPN.com. The Bucs placed Williams on the PUP list on Tuesday afternoon, meaning he won't be available for the first six games. After that, a three-week window opens during which Williams can begin practicing, and the team will have to decide whether to activate him or place him on the injured reserve list for the rest of the year.