Second-round draft pick Menelik Watson's first practice of training camp lasted less than 30 minutes Thursday 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.
Defensive tackle Pat Sims, also making his first appearance of camp, 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.