The Minnesota Vikings’ offensive line is facing quite the conundrum. They lost starting right tackle Phil Loadholt for the season during their second preseason game due to an ankle injury. Then center John Sullivan suffered a back injury and was placed on injured reserve with the designation to return. He isn’t eligible to return until Week 9. Wednesday, left guard Brandon Fusco missed practice because of a concussion, but returned in a limited capacity Thursday. The fifth-year guard was a full participant in Friday’s practice and is listed as questionable, meaning a 50-50 chance he plays..

His participation and gradual improvement suggests that he will be able to play Sunday, but he still needs to pass the baseline test. With concussions, anything can happen at any time. Jeremiah Sirles, who was acquired from the San Diego Chargers just before the regular season started, is expected to fill in for Fusco, assuming the veteran guard is unable to play.

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“When a guy sits out of practice you have to have a plan and we have a plan if Brandon plays and we have a plan if he can’t play,” offensive coordinator Norv Turner said after Thursday’s practice. “So we’ll be prepared either way.”

According to Mike Florio of Pro Football Talk, the NFL and NFLPA have launched an investigation to find out if the ATC spotter at TCF Bank Stadium for the Vikings game against the Detroit Lions did in fact miss Fusco suffering the concussion. Florio cites a league source as telling him that the investigation is aimed towards “whether or not the spotter failed to recognize and/or to take action in response to the apparent struggles of Fusco to get to his feet after a block that involved helmet-to-helmet contact.” The NFL implemented an ATC spotter at every game to look for possible concussions. They are independent from either team and have the ability to stop the game in order to get players off the field that may need medical attention for a concussion.

The only other player on the Vikings’ injury report is defensive tackle Shamar Stephen. The second-year defensive tackle has been on the injury report all three weeks this season with a knee injury. He has now been listed as probable for all three games this season.

While the Vikings have just two players on their injury report, the Chargers have 10 on theirs, including four players that missed all three practices this week. They list strong safety Jahleel Addae (ankle), WR Jacoby Jones (ankle), guard Johnnie Troutman (arm) and outside linebacker Tourek Williams (foot) as out. Guard D. J. Fluker (ankle), tight end Ladarius Green (concussion) and cornerback Jason Verrett (foot) are questionable. Finally, outside linebacker Kyle Emanuel (shoulder), guard Chris Hairston (knee) and center Chris Watt (groin) are probable for the Chargers.

In other Vikings injury news, Sullivan spoke to the media Thursday for the first time since having surgery on his back a couple weeks ago. He spoke positively about the rehab process thus far.

“I think (the doctors) were waiting for some more information on how things looked once they got in there,” he said. “And to find out the next day that my season’s not over, that it’s just delayed, that was great news. I have something to look forward to and I’m going to be back this year helping this team win.”

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Prior to this season, Sullivan has played all but three games in his seven-year NFL career. This is the first time he has dealt with back issues. Doctors told the center that the rest of the disks in his back looked good and he should not have re-occurring issues with his back.

“There’s a measure of guilt,” Sullivan said about sitting out. “And I’ve spoken with my wife and the rest of my family and my support system, the training staff here, and I understand it’s completely illogical to feel guilty about being injured, especially in this sport. But you just can’t help but feel like you’re letting people down.”

Probable (75 percent chance player will play):

Shamar Stephen, defensive tackle (knee)

Questionable (50 percent):

Brandon Fusco, guard (concussion)

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Joseph Gunther is an avid fan of Minnesota sports, including football, hockey and baseball. He covered a wide variety of sports while attending Hastings College in Hastings, Neb. While at Hastings College, he was a part of the first collegiate media group to broadcast a national tournament via television, radio, internet and newspaper at the 2004 NAIA Division II Women’s Basketball Tournament. He grew up in the Twin Cities playing three years of varsity football in high school. Joseph is a freelance writer covering all things NFL. His work can be found on Examiner.com.