The moves came Tuesday, two days after Bradfield was benched in a 41-10 loss at Washington that included a franchise-record 10 sacks. Bradfield was replaced by veteran Sam Young in the second half.
Young or Austin Pasztor, who missed the last month with a broken hand, will start Sunday against Indianapolis.
Lewis sustained a high-ankle sprain against the Redskins and will miss six to eight weeks. He was placed on IR/designated for return, meaning he can't practice for six weeks and can't return to the active roster for eight weeks.