EDEN PRAIRIE, Minn. (AP) - While the Minnesota Vikings conducted practices this past month, John Carlson watched from behind the huddle, a white ball cap on his 6-foot-5 frame signaling his nonparticipation in the drills.

As closely as he studied his new team's playbook and tried to grasp his assignments, Carlson's sprained medial collateral ligament in his left knee kept him from full immersion in the offense until returning to the field this week. With the season opener less than two weeks away, Carlson has plenty of catching up to do.

Carlson missed last season with Seattle because of a torn labrum in his left shoulder. So he hasn't played in a real NFL game since the Seahawks were in the playoffs after the 2010 season.