Wide receiver Michael Crabtree was held out of practice Wednesday due to a calf injury, the 49ers disclosed on their mandatory participation report.

It's the second leg injury for Crabtree from the start of training camp up to the 49ers' first regular-season game. He sustained a hamstring injury that kept in out of action for 16 days during training camp. Crabtree's availability for the regular-season opener on Sunday against the Dallas Cowboys is not known.

Crabtree is not the only 49ers’ starter whose status is in question. Right tackle Anthony Davis, who did not suit up for an exhibition game due to offseason shoulder surgery, now has a problematic hamstring.