Robert Griffin III left Sunday's game against the Atlanta Falcons with a head injury, when the shoulder of linebacker Sean Weatherspoon struck RGIII's head as he attempted to slide in bounds. The injury has been diagnosed as a concussion, according to ESPN's Adam Schefter.

Now that the Redskins know the extent of the injury, Griffin III will need to clear the NFL's concussion protocol this week if he hopes to play in next Sunday's game against the Minnesota Vikings. This process involves being cleared by both a team trainer and a league-appointed overseeing trainer designed to prevent players returning from injury too quickly.

If Griffin III is unable to play next week against the Minnesota Vikings, it's likely the Redskins will yet again rely on fellow rookie and fourth-round pick Kirk Cousins. Stepping in for RGIII this afternoon, Cousins completed five passes for 111 yards, along with one touchdown and two interceptions.

This story originally appeared on SBNation.com.