MANKATO – Sunday was a good day for Vikings kicker Blair Walsh, who signed a four-year, $14 million contract extension that will make him the NFL's fourth-highest paid kicker behind only Stephen Gostkowski, Sebastian Janikowski and Robbie Gould.

Walsh, who will be under contract for five more years total, was thanking the organization and telling reporters about the value of eliminating a distraction before the first practice of training camp when defensive end Everson Griffen and cornerback Captain Munnerlyn walked by yelling "New money!" and "Big money!"

Of course, big money tends to come with even more pressure. Not that the 25-year-old Walsh seems to mind.

"Being in the top five [financially] drives you to prove everyone right," said Walsh, whose extension includes $5.25 million in guaranteed money. "It's nice to have security and get an extension. But it makes you even more hungry. I'm just going to keep doing what I've done my entire career, and that's perform."

Walsh is coming off a career-low 74.3 conversion rate in his first of two seasons playing home games outdoors. But his 84.5 career percentage (87 of 103) ranks 13th in NFL history and includes a 70.8 percent mark (17 of 24) on attempts from 50 yards and longer.

"This extension stays true to our philosophy of drafting young talent, developing them in our system and rewarding their success," General Manager Rick Spielman said.

Harris tops RG battle

A year ago, then-tackle Mike Harris was forced to play guard for the first and only game of his life when a freak injury situation felled two interior linemen on the same play at Buffalo. Sunday, camp opened with Harris at the top of the tentative depth chart at right guard.

Coach Mike Zimmer said the team has scrapped plans to move rookie T.J. Clemmings from tackle to right guard. Rookie Tyrus Thompson, David Yankey and versatile career backup Joe Berger also will be given looks at right guard.

"[Harris] has played it in the past, and we just felt like we weren't ready to stick a rookie in there right away and say, 'Hey, you're the guy,' " said Zimmer, who took a similar approach at middle linebacker, where Audie Cole is working with the first team ahead of rookie Eric Kendricks.

Harris said he's already comfortable with his second opportunity at guard.

"I feel like I've proven myself that I can play," said Harris, who started last year's final five games for injured right tackle Phil Loadholt. "I know I haven't played a lot of guard. But it's the NFL. You got to fit in where you can get in."

Matthews to IR

Linebacker Casey Matthews, who injured his hip jumping over a hurdle during the offseason conditioning program, was placed on season-ending injured reserve Sunday. Meanwhile, cornerback Josh Robinson, who injured a pectoral muscle while falling on the field during an offseason practice, was placed on the active/physically unable to perform (PUP) list. Zimmer wouldn't reveal how long he expects Robinson to be out.

Defensive tackle Shamar Stephen, a valuable part of the line rotation as a rookie last year, was placed on the non-football injury list along with rookie free agent receiver DaVaris Daniels. Stephen is expected to miss three days at most because of a knee that became swollen on the flight to Minnesota.

Linebacker Anthony Barr, who is trying to bounce back from two separate knee injuries since late last season, went through individual drills but worked on his conditioning during team drills.

Pectoral problems

Robinson was the fourth Vikings player in the past year to suffer a pectoral injury. And that, Zimmer said, was the final straw that forced the coach to orchestrate a team-wide review of the injuries and a search for ways to try and prevent them.

"I don't know if they're preventable, but it's my job and my responsibility to look into every possible way that we can not have those," Zimmer said.

Guard Brandon Fusco and Loadholt suffered season-ending injuries in games last season. Defensive end Brian Robison was injured while lifting weights. All are back now.

Zimmer said the team will be working more to strengthen supporting muscles such as the rotator cuff and do more to warm up before lifting. They've also been instructed on the importance of being attentive spotters for teammates during heavy lifting periods.