Oakland Raiders quarterback Terrelle Pryor received clearance to practice on Thursday, though his availability for Sunday's game against the Washington Redskins still remains very much in question.

Pryor still needs to pass several tests in order to be given the go-ahead to play against the Redskins. The talented third-year pro is recovering from a concussion he sustained late in the fourth quarter of the Raiders' 37-21 Monday night loss in Denver.

Though Pryor took part in a limited number of drills during Thursday's session, backup Matt Flynn has taken the majority of reps with the first-team offense during the week.

"There are still some hurdles he has to clear," Raiders head coach Dennis Allen told reporters Thursday. "I hope we have a definitive answer sooner rather than later. When the doctors clear him for full participation, that's when we'll know whether he can play in the game or not."

Flynn, who was beaten out by Pryor for the No. 1 job during the preseason, started a pair of games during his four-year stint with Green Bay from 2008-11. The six-year veteran has thrown for 1,100 yards with nine touchdowns and five interceptions over his career.