MANKATO – There will surely be moments when Vikings coach Mike Zimmer isn't as friendly with NFL officials, but this week he is graciously hosting a group of them in Mankato.

A five-team crew of NFL and NCAA officials led by veteran NFL referee Carl Cheffers is here at training camp to educate Vikings players and coaches on this year's rule changes and new points of emphasis for officials, which include an heightened focus on pass interference, defensive holding and illegal contact between defensive backs and wide receivers.

"It's good to get them in and the good thing about us, I think all coaches, we adjust to the rules and try to play within the rules and try to do things the right way and try to keep the integrity of the game right," Zimmer said. "We just coach different and we have to do what we have to do to avoid penalties and still be able to play a tough, physical brand of football."

Thursday night, Cheffers' crew met with Vikings players and showed them a video from the league explaining the rule changes and how other existing rules will be applied differently on the field going forward. The officials were on the field beforehand to give players hands-on individual instruction where it was needed. They will be in camp through Saturday.

Zimmer said the instruction will be good for his players, specifically the defensive backs, who will be scrutinized by officials. But he says the new points of emphasis won't affect the way he coaches.

"I don't really have to change anything because I teach within the rules all the way anyway," he said.

Among the new rules the officials will discuss with the Vikings is the one regarding the use of trash talk and racist or anti-gay slurs on the field, which will now result in an unsportsmanlike penalty.

Praise for Patterson

Count Greg Jennings among the many who believe a breakout season is in store for fellow wide receiver Cordarrelle Patterson, who had 45 catches for 469 yards and four touchdowns as a rookie.

"There is no ceiling to his potential. There really isn't," Jennings said. "If he's willing to put in the time, the potential is there, the athletic [ability]. He has everything that he needs."

Jennings said that for Patterson to take a leap forward in his second season, the speedster needs to keep improving his route running and develop a better understanding of coverages and what defenses are trying to do to stop him.

"Once you get to the comfort level to where you line up, see what the defense is doing and you react, that's when you're playing you're freest," Jennings said.

Blanton still sidelined

Safety Robert Blanton, who injured his hamstring during Monday's practice, remains sidelined, and Zimmer said the Vikings don't know how long he will be out. In his absence, the Vikings gave the majority of the first-team reps to Jamarca Sanford and Antone Exum.

Cornerbacks Captain Munnerlyn and Josh Robinson, who have also had hamstring issues, both practiced. Munnerlyn participated in team drills after being limited to just individual work Wednesday.

Rookie tight end A.C. Leonard, who left Wednesday's practice because of a headache, did not practice.