NAPA, Calif. >> Jon Gruden called off practice today, ending his first training camp back with the Oakland Raiders a day earlier than originally planned.

No reason was given for the change, which caught a few people by surprise. A DJ who plays music during the workouts was setting up his equipment as usual and a handful of fans showed up, only to be turned back at the security gates.

Instead of going through a light practice, as is customary on the final day of training camp, players rushed to pack their bags and sped out to make the 60-mile drive south to the team’s headquarters in Alameda.

The switch also gives the players an extra day of rest before Saturday’s preseason game against the Los Angeles Rams. The two teams also meet in the season-opener Sept. 10.

“It’s a preseason game and we have a lot of really tough evaluations to get through,” Gruden said earlier this week. “We’re going to really continue to use this as an evaluation. You’re going to see a lot of players playing a long period of time that are going to get a chance to show us they belong here. That’s how we’re looking at this game.”

The Raiders made it through their three-week camp without any major injuries, although 2017 first-round draft pick Gareon Conley and newly acquired wide receiver Martavius Bryant missed long stretches of time due to a variety of injuries.

The two most significant developments were Khalil Mack’s holdout and three-time Pro Bowl left tackle Donald Penn’s move to right tackle to make room for first-round pick Kolton Miller.

Mack is entering the final year of his contract and did not report to camp. Mack also skipped the entire offseason workout program in hopes of pressuring the Raiders into offering a new deal.

Instead, the two sides remain apart as negotiations continue in hopes of getting the 2016 Defensive Player of the Year into practice.

“I don’t think it’s been a distraction,” Gruden said. “It’s obviously, for me, been disappointing. You want to have your best player here. This guy is really a great guy, too. I’m disappointed we don’t have him here. Going to try to get him here as soon as we can. In the time being, you got to move on. You’ve got to get up and go to work.”

Mack is already fifth on the Raiders’ all-time list with 40 ½ sacks.

Penn missed all but the final two practices of training camp recovering from Lisfranc surgery. The 35-year-old, who received a $21 million, two-year extension after holding out for most of camp in 2017, agreed to restructure the deal and was informed during those negotiations that he would be moved to right tackle.

Part of that is because of Miller, the 15th overall pick who is likely to be the starting left tackle when the regular season begins.

Gruden was quick to point out that Penn’s move to right tackle isn’t necessarily permanent.

“By no means are we done,” Gruden said. “We haven’t settled on any starting lineups yet. We really didn’t want to disrupt Kolton’s status right now without being sure where Donald was exactly physically. This is an opportunity to get Penn back on the field with us. Not only test the ankle, test his conditioning. Get his timing down. Get back in the channel of our offense.”