NAPA, Calif. -- Second-round pick Menelik Watson's first practice of training camp lasted less than 30 minutes Wednesday before the Oakland Raiders' offensive lineman left the field after re-injuring a calf muscle in his left leg.
Watson, the 42nd overall pick and projected backup to right tackle Khalif Barnes, had been on the non-football injury list since the beginning of camp after injuring his calf in mid-July.
The 6-foot-5, 315-pound tackle jogged out to practice and took part in two offensive linemen drills before aggravating his injury. Watson angrily walked off the field with head trainer H.Rod Martin, punched a wooden bench near the team's weight room and let out a scream before going into the locker room.
A few minutes later Watson sat on the ground in the shade just outside a door of the locker room, his head down in obvious disappointment.
"This is not the way I planned on my first training camp, I've not even took a snap yet," Watson said. "It's very frustrating, especially after the spring, making good strides in the spring. I wanted to get out there and get on the field."
Watson insisted he had not hurried back after missing the first 10 practices.
"I was aware of the situation and that I had to be careful," Watson said. "I talked about it with the training staff, that we were going to take it slow. You get out there and you get your juices flowing and you're trying to push it ... and it happened."
Defensive tackle Pat Sims, also making his first appearance of camp after being taken off the physically unable to perform list, didn't last much longer. He sustained an apparent hamstring injury during blocking drills and missed the rest of practice.
Raiders coach Dennis Allen hasn't ruled either player out for the preseason opener Friday night against Dallas, but Watson said he hopes to return to practice next week.
"It'd be speculation for me to say whether they were quite ready or not," Allen said about Watson and Sims. "Our thought process was that they were ready to get out here and work. We'll see where it goes from there."
Wide receiver Jacoby Ford also left practice with an undisclosed injury and did not talk to reporters afterward.
The injuries continue a troubling trend in Allen's second season as the Raiders coach.
First-round pick D.J. Hayden still hasn't been cleared for contact after an off-season abdominal surgery. Oakland's rookie cornerback also suffered a hamstring strain in practice earlier this week and will not play against Dallas.
Linebacker Miles Burris, who started 15 games at weakside linebacker as a rookie in 2012, is also on the PUP list and hasn't practiced since undergoing knee surgery in January.
"I still don't see anybody, with the exception potentially of Miles Burris, of being a major long-term type of deal," Allen said. "Miles has not progressed like he or I anticipated."
The news wasn't all bad for Oakland.
Notes: Defensive tackle Vance Walker was excused from practice to attend the birth of his child and is questionable to play on Friday. ... Defensive end Lamarr Houston, defensive lineman Brandon Bair and linebackers Kaluka Maiava and Billy Boyko have all been ruled out. ... Allen said all four quarterbacks on the roster will play against Dallas.