Vikings linebacker Chad Greenway will be sidelined until the start of training camp as he prepares to have minor arthroscopic knee surgery. Greenway, who missed Tuesday's organized team activities at Winter Park, will undergo the procedure on his left knee on Wednesday and will miss the rest of this week's OTAs as well as next week's three-day minicamp.

Said coach Leslie Frazier: "He had a little tension in his knee. … Just some tenderness in the knee. And we ended up doing an MRI and saw some things in there that we thought we needed to go in and clean up. And that's what we're going to do."

The Vikings are due to report to Mankato for training camp July 25 with practice opening the following day.

All expectations are that Greenway will be back at full strength by then.

"We just wanted to get it done now," Frazier said, "rather than run into a situation when we get to camp where it continued to bother him and then there'd be some issues that we'd have to deal with there."

Greenway's absence isn't figured to be a big deal at this stage. But his short-term absence certainly exposes the Vikings' lack of depth at the position. During practice Tuesday, the starting linebacker trio consisted of Erin Henderson in the middle, Marvin Mitchell on the weak side and Larry Dean taking first-team reps in Greenway's place on the strong side.

Rookie Gerald Hodges, it should be noted, likely is a front-runner to leapfrog Mitchell on the weak side.

Peterson's day off

Other big-name players missing Tuesday's work were receiver Greg Jennings, defensive end Jared Allen and running back Adrian Peterson.

Jennings, Frazier said, is absent this week because of a personal issue. Allen was present at Winter Park but only in a rehab capacity, continuing to work on his left shoulder.

Peterson, meanwhile, was held out of practice by the coach's as "a day off." Though the reigning MVP doesn't seem to get that concept, asserting that he turned in an intense upper-body workout inside the Vikings' weight room.

"To be honest with you, I did more work inside there than I probably would have done out here [in practice]," Peterson said.

'A walking miracle'

Kenechi Udeze was back on the Vikings' practice field Tuesday morning, assisting with the defensive line. Five-and-a-half years after his playing career was halted by an intense battle with acute lymphoblastic leukemia, Udeze is looking to further his coaching career. He spent last season as a coaching intern with the Seahawks and was one of several guests on hand Tuesday as part of the Bill Walsh Minority Coaching Fellowship program.

"Football will always be my passion, and something that I never lose sight of," Udeze said. "But coming up on my five-year anniversary [of the bone marrow transplant] in July, I have a lot to be thankful for. I hear a lot of stories about people having to endure [leukemia] for years and years. I went through it for six months and I was just fortunate enough that my physical health and the state I went in helped me so much with my recovery."

Frazier, who was Udeze's coordinator in 2007, sees the former defensive end as an inspiration.

"I remember visiting him in the hospital and seeing what he was going through," Frazier said. "And every time I see him, I'm just amazed. It's almost like seeing a walking miracle. Because at that time, when I was visiting him at the hospital, it was a concern about whether or not he'd survive much longer."

Etc.

• Safety Darius Eubanks missed Tuesday's practice because of a hamstring injury. Cornerback Jacob Lacey was in attendance but sidelined and in a sling after having surgery to fix a dislocated thumb last week.