Source: Terrance Williams doubtful for Sunday

OXNARD, Calif. -- According to a source, the playing time of Cowboys rookie wide receiver Terrance Williams doesn't look good for the Hall of Fame Game.

Williams, a 2013 third-round pick from Baylor, appears doubtful for the first preseason game of 2013 because of a concussion. Williams suffered the concussion during a passing drill when he got tangled up with cornerback Brandon Underwood.

Williams walked off the field with a team doctor and missed the last hour of practice.

Based on the NFL's concussion guidelines, Williams has to be symptom-free for seven days before being cleared to play. With the Cowboys' second preseason game arriving so quickly, Friday, Aug. 9 at Oakland, it's unlikely Williams would be available for that game as well.

With Williams out, Dwayne Harris and Cole Beasley took the majority of his snaps with the first-team offense in practice on Friday.