GREEN BAY, Wis. -- Clay Matthews was just as surprised as everyone else to see Julius Peppers standing on the sideline and wearing a hoodie -- not pads -- under his green No. 56 practice jersey on Monday.

As noted earlier, it was the first time that Peppers has missed a practice since he signed with the Packers in 2014.

It’s now also the first time he’s been on the injury report -- even though he isn’t injured. The Packers said Peppers’ lack of participation in practice was “not injury related.” It’s also not an illness since he was in attendance while another sick player, cornerback Demetri Goodson, was not.

The only other explanation: It must have been a day off for the 35-year-old, 14th-year veteran.

“They ruined his two-year streak,” Matthews said. “I don’t think that was Julius’ call. I wouldn’t put too much emphasis on that. He’ll be out there. We’re just making sure our workhorse is ready for us to get after the quarterback.”

Peppers was not available to reporters in the locker room after practice, but there’s little doubt the team’s sack leader with 6.0 will play on Thursday at the Detroit Lions. He has played in 213 of a possible 219 games during his career. Only two of the missed games, both in 2007, were because of injury. The other four came during his rookie year of 2002, when he served a four-game suspension.

Peppers never has had an injury in his career that required surgery, prompting his agent, Carl Carey, earlier this year to call him “a Man of Steel.”

Here’s the full injury report:

So Julius Peppers doesn't have an injury after all. It appears he was just given the day... https://t.co/9JYijLFU7s pic.twitter.com/Slqobak7Bn

— Rob Demovsky (@RobDemovsky) November 30, 2015