TAMPA, Fla. -- Tennessee Titans rookie quarterback Marcus Mariota sprained his left MCL Sunday, and Tampa Bay Buccaneers coach Lovie Smith took notice.

Smith's teams also starts a young quarterback, No. 1 overall draft pick Jameis Winston. And Smith knows there's a limit to how much a coach can do to prevent an injury.

"You never know when an injury will happen," Smith said Tuesday. "You do everything you can to safeguard against it. But beyond that, it's a contact sport. The object is to tackle, to get them down, to get the guy with the ball down every play. So injuries are going to happen. You just hope you're lucky. But you can't really think about that an awful lot."

Titans coach Ken Whisenhunt called the hit on Mariota by Miami Dolphins defensive end Olivier Vernon "bulls---" after the game. ESPN Titans reporter Paul Kuharsky reported that the injury is a Grade 2 MCL sprain and that Mariota, who was drafted second overall in April behind Winston, could face a three- to four-week recovery.

Mariota has faced more pressure than Winston has this season. Mariota has been sacked 19 times in Tennessee's 1-4 start, and Winston was dropped on 11 occasions as Tampa Bay earned a 2-3 mark before its bye week.

"As far as protecting our quarterback, we do think about that," Smith said. "We want to protect him as much as we possibly can. Limit the amount of times he runs, and just limit the amount of times that he's exposed to what those big, bad defenses are doing. But you can only do that so much."