Williams ran for 140 yards, including a 69-yard scoring jaunt in the second quarter. The Panthers (7-2) had only 219 total yardage in the contest.
Julius Peppers registered three sacks and forced two fumbles for Carolina.
Panthers' quarterback Jake Delhomme was intercepted four times. Delhomme completed just 7-of-27 passes for 72 yards and threw a 3-yard touchdown pass to Muhsin Muhammad.
Andrew Walter was 14-of-32 passing for 143 yards, with two interceptions, for the Raiders (2-7). Walter played in place of JaMarcus Russell, who has an injured knee.
Justin Fargas carried 22 times for 89 yards for Oakland.
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