Robert Griffin III diagnosed with concussion

Washington Redskins quarterback Robert Griffin III suffered a concussion in Thursday's preseason game against the Detroit Lions.

Head coach Jay Gruden confirmed that Griffin did not pass the league's concussion protocol, but couldn't put a timeline on how long he will be out.

"I'd imagine he'd still be our starter," Gruden said when asked if Griffin would lose his job because of the injury, before adding, "It was not a very good performance by our first-team offense, to say the least."

Griffin took a number of big hits during the first two quarters of the Redskins' loss to the Lions, eventually leaving after Corey Wooton landed on him following a fumble.