Left guard Brandon Fusco practiced for a second straight day, but as of this writing, he has not yet been cleared through the NFL's concussion protocol.

Fusco has been listed as questionable for Sunday's game on the official injury report. But coach Mike Zimmer said a little bit ago that the Vikings expect to know sometime soon whether Fusco will be available for Sunday.

If Fusco is not cleared to play against the Chargers, the Vikings could turn to Jeremiah Sirles, who was acquired from the Chargers three weeks ago.

"It just kind of happens the way it happens," Sirles said "You never foresee anything happening like this. But if you get a chance, an opportunity to go and play, it would be kind of fun to play against the team you started with."

Sirles signed with the Chargers last spring after going undrafted out of Nebraska. He ended up making the team, starting one game and playing in another when one of the Chargers' starting linemen suffered an injury.

"If you're not a starter, you have to prepare like a starter because you never know when your number is going to be called," the 24-year-old said Colorado native said. "That happened to me last year. [I was a] backup and all of the sudden the guy went down and you kind of get thrown in there."

The Vikings traded a sixth-round draft pick for Sirles after this preseason.

"He's a big guy, keeps his feet moving, athletic. He's got some toughness to him," Zimmer said. "We've been practicing him at three positions actually."

Rookie Austin Shepherd and second-year lineman Zac Kerin are the other candidates to start from the active roster if Fusco is not cleared to play.

In other injury news, nose tackle Shamar Stephen, who played last week and was a full participant in practice this week, is probable for Sunday.