ALLEN PARK -- Detroit Lions cornerback Drayton Florence suffered a concussion against the Green Bay Packers on Sunday, but the injury wasn't diagnosed until Monday morning.

Florence briefly left the game following the Lions' first defensive snap after tackling Green Bay wide receiver Randall Cobb.

"The official removed him from the game, our guys checked him, and he passed all the (concussion) tests on the sideline," Lions coach Jim Schwartz said. "He returned to play, played pretty well, and didn't have any signs as we moved forward. He didn't seek any treatments, wasn't having any symptoms after the game."

Schwartz said Florence woke up on Monday with a headache and was diagnosed with a concussion by the team's medical staff.

It was Florence's first action since breaking his forearm against the San Francisco 49ers in Week 2. He mad six tackles in the loss, but declined interview requests after the game, saying he needed to get treatment on his arm.

In addition to Florence's injury, it's looking like offensive tackle Jeff Backus will be unable to go this Thursday when the Lions host the Houston Texans. If he sits, it will be the first game he's missed a game in his 12-year career, snapping a string of 186 consecutive starts, the third-longest active streak in the NFL.

"We'll see how he does, but it's probably going to be doubtful that he'll be able to play on a short week like this," Schwartz said.

As for Louis Delmas, Schwartz said the team will have to "wait and see" with the starting safety. Delmas did not practice on Monday.