Right tackle Brian O'Neill, cornerback Mackensie Alexander, defensive end D.J. Wonnum and tight end Chris Herndon returned to Vikings practice Thursday, a day after all four were not seen at TCO Performance Center and listed with "not-injury related" designations on the injury report.

"All we heard was that [Alexander] tested positive for COVID," cornerback Patrick Peterson said Thursday. "A lot of crazy things going on this year, you never know what to expect day-in and day-out. All you have to do as players is make sure that you're keeping yourself out of the way of that because, obviously, it can hurt the team."

It's possible Alexander and the other three players were cleared through retesting after initial positive tests.

The Vikings had a full house at Thursday's practice with everyone on the active roster at least participating in a limited capacity. That includes linebacker Anthony Barr, who was held out last week in Los Angeles due to his lingering knee issue.

Linebacker Ryan Connelly also was cleared to return from the reserve/COVID-19 list, where he'd been isolated since Nov. 8. He was limited in Thursday's practice. Three players remain quarantined: defensive end Kenny Willekes, safety Josh Metellus and fullback Jake Bargas.

Six Packers players did not practice Thursday: quarterback Aaron Rodgers (toe), left tackle David Bakhtiari (knee), running back Aaron Jones (knee), tight end Marcedes Lewis (rest), and receivers Allen Lazard (shoulder) and Malik Taylor (abdomen).

Peterson: 'Thank God it's over'

Peterson, in his 11th NFL season, spent his longest injury-related absence away from the field the only way he knew how, by still stretching with the team in warmups and traveling to road games. Routine is important to Peterson, who also tried to expand his horizons by requesting a headset to wear during games so he could listen to coaches communicate.

"Trying to get a feel for the offense and understand how you want to call certain defenses," Peterson said. "Understand when you want to send pressure. When you're in the game, you can't really hear the calls. You're just waiting for the call to come out."

Before this hamstring injury, he'd been available for 160 of 166 NFL games — only missing six games due to a suspension. Sitting out required an adjustment.

"It definitely was miserable," Peterson said. "Something I've never had to do before, but thank God it's over."

Who's starting at center?

Coaches are giving both centers Garrett Bradbury and Mason Cole reps with the starting offense, according to coordinator Klint Kubiak, as Bradbury returns from a COVID case. Kubiak said they'll decide "as the week goes on" who starts, adding sometimes players need additional time before returning following a bout with COVID.

"We've had a year of experience of this with other guys that have had it," Kubiak said. "Some bounce right back, some take a while to get their energy back. So we're taking it one day at a time. I'll say that [Bradbury] has done a great job and he's doing everything he can to get back on the field."

A more patient foe

Defending Packers quarterback Rodgers is difficult, in part, because the future Hall of Famer isn't in a hurry to snap the ball. He'll wait and wait until the defense tips its hand to a certain coverage or blitz that's coming, which is in stark contrast to Chargers quarterback Justin Herbert, whom Vikings coaches schemed multiple unblocked blitzes against. Rodgers has a knack of figuring out what you're doing before you do it.

"What we have to do is find a way to make him have to read through that process after the ball is snapped," co-coordinator Andre Patterson said. "Instead of him figuring it out before the ball is snapped. If you look at it, he snaps the ball later on the time clock than any quarterback. He lets it come down to three or four seconds."

College vs. pro?

Rivalry games in the SEC have a different feel for receiver Justin Jefferson than the division battles like Sunday's game against Green Bay. But to be fair for the 22-year-old phenom, he's yet to play a Vikings-Packers game in front of a home crowd at U.S. Bank Stadium.

"I feel like in college it's way more intense," said Jefferson, who played for LSU. "I don't know why, but I definitely feel like it's way more intense in college. But in the NFL, you definitely know the rivalry teams when they come to town or when you go to them. Just the game plan, the way it's set up, the talk that's in the locker room."