The former Memphis star hobbled off the field in the final minute of Carolina's win over the San Francisco 49ers last weekend and hasn't practiced since. The team has provided no update on the injury and Williams hasn't talked to reporters.
After Williams rushed for more than 1,100 yards last season, the 2009 Pro Bowl selection has been held to 361 yards on 87 carries. Stewart has 148 yards on 50 carries.
Mike Goodson will likely be the No. 2 back Sunday.