Cowboys rookie wide receiver Terrance Williams left Friday's practice and was being tested for a possible concussion. If Williams who collided with cornerback Brandon Underwood during a passing drill fails the baseline test he will miss the Hall of Fame game against the Miami Dolphins on Sunday. Williams has to be symptom-free for a certain amount of days before being cleared to play. The Cowboys' second preseason game arrives quickly -- Friday Aug. 9 at Oakland -- and he could miss that game as well. With Williams missing the last hour of practice Cole Beasley replaced him as the slot receiver and Dwayne Harris took over as the No. 3 receiver on the depth chart.