Amari Cooper an observer at Raiders practice

ALAMEDA, Calif. -- Oakland Raiders receiver Amari Cooper was a spectator at the beginning of practice Tuesday, while free safety Reggie Nelson was working with a trainer on a side field.

There were no updates on the condition of either player as practice began.

The Raiders were in full pads and while Nelson was fully dressed, Cooper was in shorts and did not have his helmet. Cooper did, however, stretch with the team before position drills began.

Also, undrafted rookie running back Jalen Richard, who has not practiced in two weeks with a knee issue, was back.

Cooper has three receptions for 27 yards this preseason, including a 20-yard catch in traffic at the Green Bay Packers last weekend. He did, however, come under scrutiny for not fully fighting for the ball on a long pass from Derek Carr against the Packers that was intercepted.

The Raiders resume practice Wednesday and practice again Thursday before playing host to the Tennessee Titans in both teams' third exhibition game Saturday. The Raiders travel to Tennessee for a Week 3 game in the regular season.

“We’re going to play our guys; we need the work,” coach Jack Del Rio said. “But, obviously, both sides, I’m sure, will hold a few things back. You’re not going to show everything you want to do in the regular season in a preseason game.”