ASHBURN, Va. -- After further tests, Washington Redskins quarterback Robert Griffin III has not been cleared to play Saturday night against the Baltimore Ravens, casting doubt into his availability for the season opener in two weeks.

Griffin suffered concussion-like symptoms in an Aug. 20 preseason game against the Detroit Lions, but practiced all week and was initially cleared by independent neurologist Robert N. Kurtzke.

However, the team reversed course Friday.

In a statement released by the team, Kurtzke said, "Per discussion with Neuropsychologists and with Anthony Casolaro M.D., we had anticipated yesterday that the patient would be cleared for full participation in gameplay this weekend; however, upon further scrutiny today of the neuropsychology data, I agree with the neuropsychologist that he should be held from gameplay this weekend and be retested in one-two weeks before a firm conclusion to return to gameplay can be made."

It was unclear even Thursday whether Griffin had indeed suffered a concussion. He could not point to which play it might have happened -- or if it had occurred on the final play of his night, when a Lions player fell on him.

The Redskins called it a concussion after the game, but Griffin declined to confirm that he indeed had one, saying: "You have to talk to the people who report that stuff." Still, he practiced throughout the week and sounded a note of caution in his news conference Thursday.

"I feel good, just trying to take care of everything and be as cautious as possible," he said. "It's not about anything but my family and them caring for me and my well-being. My teammates care about me and are asking about me every day. I'll just follow the protocol and see what happens."

Griffin tweeted Friday night after the Redskins' announcement that he must sit.

Trusting in God even when I don't understand why certain things happen. James 1:2-3 (NLT) — Robert Griffin III (@RGIII) August 28, 2015

The move opens the door to a possible quarterback change to open the regular season.

Kirk Cousins likely will start Saturday night against Baltimore. If Griffin isn't cleared, or if Cousins has another strong outing, then Cousins could end up starting the season opener against the Miami Dolphins.