One of the Minnesota Vikings' biggest concerns heading into the season just got even bigger. Center John Sullivan has been placed on injured reserved.

There's really nothing "short" about it. With the designation to return from IR, Sullivan will miss at least the first seven games (eight weeks) of the season. He was experiencing back spasms that forced him to miss practice towards the end of training camp. It was announced that he has undergone back surgery causing the move.

This now places two starting offensive linemen out for the beginning of the season. Right tackle Phil Loadholdt was injured in the first preseason game and he will miss the entire season.

Minnesota's offensive line will now rely on left tackle Matt Kalil, who struggled last season. Brandon Fusco remains at left guard. The center position will now be placed into the hands of 11 year veteran Joe Berger. Mike Harris will play at left guard, while rookie T.J. Clemmings takes over for Phil Loadholdt.

The Vikings open the season on Monday Night against San Francisco.