Running back Carnell ?Cadillac? Williams and tackle Luke Petitgout both will undergo season-ending knee surgery this week, a major setback for the Tampa Bay Buccaneers. Williams injured his right knee when he was tackled by Carolina safety Chris Harris at the end of an 18-yard run during the first quarter of Sunday?s 20-7 victory over the Panthers. Petitgout limped off the field after defensive tackle Kris Jenkins fell into his right leg in the second quarter. ?That?s a big blow. ... We have some people who need to step up,? coach Jon Gruden said Monday.