EDEN PRAIRIE, Minn. —Vikings center John Sullivan said Friday that a knee to the helmet caused the concussion he suffered Sunday against the Bills.

Sullivan and right guard Vladimir Ducasse, who suffered a knee injury (not due to Sullivan's helmet), left the game at Buffalo after the same play early in the first quarter and were replaced by Joe Berger and Mike Harris, respectively, for the rest of the game.

Sullivan passed the NFL's concussion protocol tests, which include different types of observed workouts and medical examination before participating fully in practice Friday.

The seven-year pro is probable this weekend when Minnesota (2-5) visits Tampa Bay (1-5) at noon (CT) Sunday at Raymond James Stadium.

Ducasse fully participated for the second straight day Friday and is listed as questionable. Berger has experience at all three interior line positions, and would likely be first in line if Ducasse is unable to play. Harris, who hadn't played guard since his youth, was the only other available active lineman last week and held his own.

Vikings Head Coach Mike Zimmer said Friday that Berger's versatility is helpful.

"He's a smart guy. He's been doing everything he's supposed to do," Zimmer said. "He's been able to play multiple positions and he's got good chemistry in the room."

MCKINNON ON THE MOVE: Regardless of who is in front of him, rookie Jerick McKinnon has a chance to record his third 100-yard game in a five-game span and second in a row. McKinnon has rushed for 302 yards in the past four games, which ranked as the fifth-most in the NFL since his career high of 135 against Atlanta on Sept. 28.

Offensive coordinator Norv Turner was asked this week about McKinnon's progression.

"He obviously flashed from the beginning and has done a good job making big plays," Turner said. "I just think he's learning how to play in this league and he's become more consistent, he's finding the correct lanes, he's understanding defenses better. He improved a lot in protection from the first game he started to the second and that's a big part of playing running back in this league and our system certainly. He's making the normal progress that you'd like to see a rookie running back make." 

TAMPA'S 2 QBS: Tampa Bay QB Josh McCown practiced fully Friday for the first time since injuring his right thumb in Week 3 against Atlanta. McCown, who signed with the Bucs during free agency, was replaced by Mike Glennon. The second year pro has posted a passer rating of 86.2 this season, which is more than 20 points higher than the rating for McCown, who is listed as questionable.

Vikings defensive coordinator George Edwards said Minnesota was able to prepare for both quarterbacks and has observed what Tampa Bay has done in the absence of offensive coordinator Jeff Tedford, who had a heart procedure earlier this season.

"Both of them have played so we can see the different style," Edwards said. "Offensively, they've pretty much been consistent at what they're doing schematically. I know they've had a change with who's calling the plays and that kind of thing. From our aspect of it, it's just to see the different positions that they're playing different guys in, the different matchup problems that they're trying to create and then schematically what they're trying to do and try to go out and try to take away what it is they're trying to do by down and distance."

RUN RUN RUDOLPH:Tight end Kyle Rudolph, who has missed the past four games and is out Sunday, continued his recovery from surgery by running through some agility drills Friday.

PARTICIPATION: Josh Robinson did not participate in Friday's practice a day after suffering an ankle injury during positional drills. He is listed as questionable. Gerald Hodges (hamstring) was limited for the second straight practice and is doubtful. Click **here** for the final injury report of both teams.

WEATHER: The temperature at the start of practice was 54 degrees Fahrenheit with slight winds and plenty of warming sunshine. The forecast for Sunday in Tampa is sunny with a high of 83 and low of 61.