Kirk (calf) continued to work on a side field at Saturday's practice, Vic Tafur of The Athletic reports.
Kirk has been tending to a calf injury since July 26 and hasn't mixed back into drills in the meantime. There seemingly is a chance he kicks off the season on injured reserve, but he could change the tune by returning to practice or suiting up for Thursday's preseason game in Las Vegas. With all of Mike Evans (quad), rookie second-round pick De'Zhaun Stribling (shoulder) and Ricky Pearsall (knee, IR) banged up at the moment, Deebo Samuel, Demarcus Robinson, Jordan Watkins and Jacob Cowing are the top healthy and available wide receivers for the 49ers.