Kevin Williams missed practice for the second consecutive day and his availability for Sunday's opener at Detroit remains in jeopardy.
Vikings coach Leslie Frazier said Williams hopefully can do some work in Friday's practice, which will determined whether he's healthy enough to play.
"We'll see if we're able to get anything [Friday]," Frazier said. "He is making improvements but tomorrow will be a big day to determine if we have a chance to get him ready for Sunday."
Williams escaped ligament damage on the cheap shot in the San Francisco preseason game, but he suffered a hyperextended right knee, a significant bone contusion and a posterior capsular strain..
Asked what he needs to see from Williams to feel comfortable putting him on the field, Frazier said, "Just see him push up against people and move around a little bit. If we can get that and see how he responds to other guys pushing up against him, that would be a plus."
If Williams doesn't play, rookie Sharrif Floyd could get the start in his NFL debut. Floyd was bothered by a minor knee injury in preseason, but Frazier said that is no longer a major issue, even though Floyd has had limited participation in practice this week.
"He's done well," Frazier said. "He looks good. It doesn't look like there are any ill effects from his injury. So full speed ahead."
Frazier said Letroy Guion "possibly" could slide to Williams' tackle position from nose tackle.
"We moved him to the nose for a reason, but circumstances might dictate that we might have to get him a few snaps there," Frazier said. "We'll see how it goes."
Limited in practice were: Phil Loadholt (knee), Cordarrelle Patterson (back), Mistral Raymond (shoulder), Guion (finger).