MANKATO, Minn. — By the time the final 15 minutes of Tuesday night's practice rolls around, the aviator sunglasses of Vikings Offensive Coordinator Norv Turner are likely to be removed.

Turner will be watching keenly to evaluate performance and see who's prepared to perform the best in spite of fatigue.

"I really put a lot of stock in how guys practice the last 15 minutes of practice as compared to the first 15 because I tell them, more and more, this game is being decided by the last four minutes in the game," Turner said after Tuesday morning's walk-through while filling in for Head Coach Mike Zimmer.

"Whatever the percentage is, 70 percent of the games were decided by a touchdown or less, so in those last four minutes, the team that's the best conditioned, the team that can still play the fastest (will prevail)," Turner said. "I always tell our guys, we go out and do two-minute and they go 12 straight plays and at the end of it we're down in the red zone and they're tired, but they're going to be tired in the game. So you have to find a way to go run full speed at the end of those situations, and that is a lot about mental toughness."

Tight end Kyle Rudolph, whose past two seasons have been bitten by injuries, changed up his offseason workout program and his year-round diet with a focus on "eating cleaner."

"My weight has never been an issue," Rudolph said. "It's not one of those things where I have to lose weight or get any more muscle to build up some armor. It was just, for me, about eating foods that will help me recover faster, making sure I get the proper amount of proteins and carbohydrates in my body after a workout so when I do go out and break down muscle, that I do recover quickly."

Rudolph said eating clean is "pretty boring," relying on brown rice, chicken and sweet potatoes, with an occasional steak mixed in.

"It's a lot more fun to go out and have cheeseburgers and French fries," Rudolph said. "Pizza is definitely a hard one as well. One of the good things I've found is Chipotle because all their food is organic. You can go in there and get chicken and brown rice and a bunch of veggies. I'm a frequent at the Chipotle in Wayzata. They pretty much know me by name now. That's one of my favorite places to go get food."

Rather than a burrito or bowl, however, Rudolph said he opts for the salad.

Chad Greenway, who is going into his 10th pro season said he's been "a little bit lucky" without having unwanted weight gain issues. He said he has become more attentive about choices as his career as progressed.

"If anything, I have a tendency to lose too much weight. I think I'm meant to be 210 pounds and of course play quarterback," Greenway joked. "It's never been too big of an issue for me. I've been able to maintain my weight within about three or four pounds so it's never been a concern of mine. You do, as you get older, become more conscious of foods that aren't necessarily good for you or things you should put in your body and I've certainly moved away from those."

PAPA SULLY: Vikings center John Sullivan announced the birth of his son, John Harris Sullivan, via Instagram. Sullivan was excused from Monday's practice.

Turner had fun in mentioning the birth to reporters, saying, "I haven't heard the name. I don't think it's Norv."

Turner said the Vikings were able to give younger players some work at center. Zac Kerin took reps with the first team Monday, and also has played guard.

"Zac is a versatile guy and he can play," Turner said. "I thought he was fine yesterday,"

PASS THE BATON: Turner was asked about the speed that Vikings receivers feature, led by Mike Wallace and complemented by Charles Johnson, Jarius Wright, Cordarrelle Patterson, Adam Thielen and Stefon Diggs.

"I have a hard time comparing players and comparing groups, but the one thing, I think we can put together a pretty good relay team with this group," Turner said. "I think they run awfully well."

Turner did say he thinks there's a difference between having speed and playing fast. He prefers the latter.