The Vikings have completed their Friday morning walkthrough at Blakeslee Stadium in Mankato and afterwards head coach Leslie Frazier and a handful of players stopped to speak with reporters. Here's your quick midday update.

The injuries have begun

Both cornerback Xavier Rhodes and receiver Chris Summers may sit out this afternoon's practice while dealing with hamstring injuries. Neither injury is expected to be serious. Nor is the groin soreness that sidelined Erin Henderson for a portion of Thursday's practice but doesn't seem to be a limiting factor right now.

Still, Henderson's temporary absence forced the microscope into the depth at middle linebacker with Audie Cole responding to the "next man up" plea. Cole, a second-year guy, played only five games last season and only on special teams last season. So in the event that Henderson were to suffer a more serious injury, the Vikings have obvious concerns.

"To say that we'd be completely satisfied with where we are depth-wise at the middle linebacker position? I couldn't say that today," Frazier said. "We need to see those guys work. This is Erin's first year as a full-time middle linebacker. Audie has never really played a game, other than the preseason."

Frazier also noted that Henderson has a leap to make in his maturation as a leader at middle linebacker, mentioning a moment in practice earlier this week when a defensive player came to consult Henderson about a defensive call and received a curt response.

"Alan [Williams] went up and talked to him about that and said 'You're in a different role now,'" Frazier said. "When those guys talk to you, you have to listen and then speak almost as if you're a coach. Otherwise they'll stop asking you questions because they don't want to get in any confrontation."

Robinson learning quickly

Josh Robinson's transition into becoming a slot cornerback is going about as well as expected, according to Frazier.

"We're much more comfortable with him today then we were say three or four days ago when we opened camp," Frazier said. "We just have to keep putting him in situations because this is all new for him and letting him gain experience. Practice along with preseason games are going to be big for him and big for our team. Because we need that position to play well for us."

Vikings ready to go under the lights

The Vikings will complete their first full week of training camp on Saturday night with a practice under the lights at Blakeslee Stadium. Frazier was asked about that event and believes it has a chance to be revealing.

"It'll be a chance for some of our young guys to play in front of a captive audience," he said. "They've been at practice. And it's great to have our fans out at practice. But it's a different environment when you go under the lights and you feel the sense that it's similar to a ball game. We're going to try to create some situations in that time that we're there on that Saturday night where they feel as if they're in a game situation. It probably helps our young guys more than it does our veterans."

For those fans hoping to see a full dose of Adrian Peterson on Saturday, Frazier said the first-team offense would probably only take a couple of series. Toby Gerhart may see some time in place of Peterson. And Saturday's scrimmage situations will all come without live contact.