Winfield, who has already missed three straight games with a neck injury, practiced on a limited basis all week. Coach Leslie Frazier said the injury showed improvement, but not enough to make him optimistic for this weekend.
"He moved around a little bit," Frazier said. "We'll see how he feels (Saturday), but I'd say he's doubtful for the game on Sunday."
Sanford and Sullivan both came out against Chicago last weekend with concussions and have yet to pass the required tests to be cleared to play.
Assuming Sanford will not play, the Vikings (1-5) will go into the game against the pass-heavy Packers without half of their starting secondary. Tyrell Johnson would start for Sanford, while the Vikings would continue to use a combination of Chris Cook and Asher Allen to fill in for Winfield. Rookie safety Mistral Raymond also likely will be active for the first time in his young career.
Joe Berger likely will get the start for Sullivan at center, snapping the ball to rookie quarterback Christian Ponder, who will be making the first start of his career. Receiver Percy Harvin (ribs), right tackle Phil Loadholt (knee), special teamer Kenny Onatolu (hamstring), linebacker E.J. Henderson (left knee) and left guard Steve Hutchinson (knee) are all listed as probable.
Copyright 2011 by The Associated Press