Allen, who has not practiced this week and appears to be a long shot to play, said he suffered a grade-3 sprain, or separation, of the AC joint in his right shoulder during the Vikings' victory over Houston on Sunday. A third-degree sprain is the most serious and often indicates a torn ligament.
If the damage is indeed that bad, Allen not only would almost certainly miss Sunday's game but could be out for two-to-four weeks. What isn't certain is if the Vikings might be putting this information out there in an attempt to surprise the Packers come Sunday.
Allen said a final decision on his status would be made by the Vikings medical staff and the coaches.
"I guess there is always hope but it's not my call," he said. "I've got two more days. I'm not really thinking about it. I want to hopefully just see how it plays out. And it's not solely on me. If it was my decision, I think you guys know what my decision would be. But coach has to do what's right for the team and (head athletic trainer) Eric Sugarman has to make sure he does what is right for my body."
Defensive coordinator Leslie Frazier said that if Allen can't play, second-year player Brian Robison would get the start at right end. The 6-3, 259-pound Robison had 4.5 sacks last year and this season has played every position on the line in a backup role.
"He did some pretty good things for us at the end of the year (in 2007) when he had to start when Ray (Edwards) was out for a period of time," Frazier said. "He has the ability to start in this league. He's really improving. He's only in his second season as an NFL player. From our standpoint his best football is ahead of him and we feel like he'll play well for us in the number of reps he'll get on Sunday. If he has to play for an extended time, we have tremendous confidence in Brian."
Robison has been used primarily as a pass-rush specialist. Frazier said Robison has improved as an early-down (run situation) player but added, "still, if there is a weakness, that's an area where he wants to continue to improve. Especially from the right end position."
Added Frazier: "He has gotten so much better in his second season and we expected that. So, we have confidence that if he's in situations on first and second down and they are trying to run the football, he'll be able to hold up and do well."