One of the most impressive young players on the Detroit Lions' roster, starting first-year cornerback Bill Bentley, left Sunday's game with St. Louis after sustaining a concussion in the third quarter, according to MLive.com's Anwar Richardson.

Bentley, who was tested multiple times on the sideline while his possible return was evaluated, did not give team doctors a clear indication that he was healthy enough to go back on the field. Lions head coach Jim Schwartz noted that his young defensive back was not official diagnosed during the game, but that he was experiencing concussion-like symptoms which led the team to play things safe.

"I don't know if he was officially diagnosed, but we err on the side of caution when it comes to it," Lions coach Jim Schwartz said. "He wasn't unconscious or anything like that where it would have been for sure. But again, if a guy is having any symptoms, we're not going to let him back in the game, and that's what happened with Bill."

An obvious blow to Detroit's already thin secondary if he's forced to miss extended time, Bentley will need to first be cleared by a non-team affiliated doctor in order to have a chance at facing off against the San Francisco 49ers on Sunday Night Football next week.

Head over to Pride of Detroit for more Lions coverage and Week 1 reaction, and be sure to check out SB Nation's NFL hub for more news and analysis from around the league.