ARLINGTON, Texas -- Detroit Lions wide receiver Amon-Ra St. Brown was ruled out in the first quarter of Sunday's 24-6 loss to the Dallas Cowboys with a concussion.
After catching a short-left pass from quarterback Jared Goff, St. Brown took a hit from Cowboys linebacker Anthony Barr and shook his head after the play.
An official flagged the injury immediately, and St. Brown was evaluated in a blue medical tent before being taken to the locker room with no helmet. He was then ruled out for the game.
Lions coach Dan Campbell confirmed after the game that St. Brown is in the concussion protocol. Under the league's new adjusted concussion protocol, Campbell says St. Brown was automatically ruled out when the official pulled him off the field.
"I just talked to him, and he gave me a thumbs-up, but who knows what that means," Campbell said after the loss. "We know what kind of player [St. Brown] is, and any time you lose a player like that it's not easy."
St. Brown also missed the Week 4 loss against Seattle with an ankle sprain.
He told ESPN earlier this week that he felt his health was "85-90%" coming off the bye week, during which he visited family and friends in California and received treatment from a physical therapist on his ankle.
St. Brown entered the Cowboys game with three receiving touchdowns and a team-high 27 receptions.