Bucs RB Doug Martin's night got off to a bad start and got only worse. But he did escape a major injury.

A missed block by Martin contributed to QB Josh Freeman taking a sack on the Bucs' first offensive play in Friday's 25-21 preseason loss to the Patriots. Later Martin in pass protection again went low on Patriots DE Chandler Jones and one of Jones' knees struck the top of Martin's helmet.

Martin was wobbly but went to the locker room under his own power. He said he passed concussion tests and could have returned to the game.

"It was just a tough play" Martin said. "Things happen."

If Martin had suffered a concussion he would have been out indefinitely.

Treatment of concussions is highly regulated by the NFL. Depending on the results of required tests players can be sidelined in subsequent weeks and can be barred from participating in practices until they have satisfactory test results.