EDIT: Some positive news from Tom Pelissero, who reports that Carlson's injury is indeed an MCL sprain. No tear, and no surgery will be needed. Speculation is that he will miss two to three weeks, meaning he will still be ready for the start of the regular season. -Chris

A bit of bad news to come out of Mankato today, as it appears that tight end John Carlson has become the first major casualty of the pre-season for the Minnesota Vikings.

Carlson, who the Vikings signed to a five-year contract as an unrestricted free agent after he began his career in Seattle, sprained the medial collateral ligament in his knee during Tuesday's practices. Carlson was going to have an MRI later in the day to see if it was anything more than that, but that was the initial diagnosis.

Carlson missed the entire 2011 season because of a shoulder injury, but had a couple of good seasons with the Seahawks. Taken by Seattle in the second round (38th overall) of the 2008 NFL Draft, Carlson started his career with back-to-back 50-catch seasons, averaging more than 11 yards per catch and finding the end zone 12 times. He dropped off a bit in 2010 before missing all of last season.

His absence will open up the door for a few players to showcase themselves at the tight end position, notably fourth-round selection Rhett Ellison. Mickey Shuler and Allen Reisner will also get extended looks at the tight end spot while Carlson is sidelined. Shuler and Reisner might be battling for one roster spot, so it will be interesting to see if either of them step up over the next couple of weeks.

Eric and Arif will be by with more of their awesome Training Camp coverage momentarily.