Four days after missing the bus in Chicago, Adrian Peterson finally divulged an explanation.

"I overslept," the Vikings running back said Thursday. "I slept through the alarm, through the calls. I overslept. I had the wake-up call set up. I slept through it. That's it."

Peterson arrived at Soldier Field on Sunday morning separate from the team, needing to take a taxi from the JW Marriott in downtown Chicago to the stadium. He was in the locker room approximately 90 minutes prior to the noon kickoff and said that missing the bus didn't cause a significant disruption to his usual routine.

"Not much," Peterson said. "I got in there, got warmed up, got ready for the game."

Vikings coach Leslie Frazier said Monday it was "a big deal" that Peterson was not on the team bus to the game, noting that "anytime one of your leaders is not where he is supposed to be, it's not good."

The NFL's leading rusher had 108 yards on 18 carries against the Bears, but lost two fumbles in a 28-10 defeat.

Peterson said he and Frazier met to sort through the mini-drama and have now turned the page.

"It's over and done with," Peterson said. "So I'm moving forward, worrying about what's important now."

Harvin sidelined

Percy Harvin did not participate in Thursday's practice. The receiver still is bothered by his sprained left ankle and held back after testing the ankle Wednesday.

The Vikings moved Thursday's practice outside and Frazier said Harvin did a little bit of work with receivers coach George Stewart but did not do anything with the offense.

Said Frazier: "The fact that we were out here on the grass, we wanted to just give it another chance to see where he is. And then we'll try him out tomorrow if we can."

The Vikings' final practice of the week will begin about 11 a.m. Friday as they finish their preparation for Sunday's game in Green Bay. Frazier hopes to see Harvin do more Friday but is not yet banking on the dynamic receiver to be able to play this weekend.

"He's got to work through it," Frazier said. "Pain tolerance is the key."

Tight end Kyle Rudolph, who missed Wednesday's practice because of a shoulder strain, returned Thursday.

Major test

They've faced Brandon Marshall. They've faced Larry Fitzgerald. They've faced Calvin Johnson twice.

But the Vikings haven't faced anything like they're going to face on Sunday against the Packers at Lambeau Field.

The Packers are one of only three teams that have four receivers with at least 35 catches and two touchdowns. Of those three teams, the Packers are the only one to have those four targets and their best receiver, Greg Jennings, returning this week after missing the past seven games because of a sports hernia surgery.

"The biggest test we'll face all year from a group standpoint," Vikings defensive coordinator Alan Williams said. "You have to defend everybody they have on the field. You can't just take away one guy. If you take away one guy, another one will hurt you. We'll have to be honest and play sound, fundamental football and everyone will have to stand up and do their job this week because they all can hurt you."

The Packers have Randall Cobb (58 catches, 613 yards and seven TDs), Jordy Nelson (45 catches, 648 yards and six TDs), James Jones (42 catches, 495 yards and eight TDs) and tight end Jermichael Finley (35 catches, 388 yards and two TDs).

The only other teams with four targets that have at least 35 catches and two TDs? Peyton Manning's Broncos and Drew Brees' Saints.