Orlando Magic point guard Jason Williams will have arthroscopic surgery on his left knee Thursday and will miss about four weeks.

Magic coach Stan Van Gundy says Williams' knee has been problematic for weeks and was injured again during training camp this week. An MRI showed loose cartilage but no tear. Williams could be back in time for the Oct. 28 regular-season opener.

Williams was Orlando's No. 2 point guard backup last season, starting 18 games while starter Jameer Nelson was injured. But Williams was expected to have a smaller role this season after the Magic signed free agent Chris Duhon to be Nelson's primary backup.

Williams has averaged 10.8 points and six rebounds per game in 11 NBA seasons. He also helped the Miami Heat to the 2006 NBA title.