Niners hopeful on receiver Johnson

Posted by ESPN.com's Mike Sando

KIRKLAND, Wash. -- The 49ers' practice with the Raiders produced one fight and a hamstring injury for San Francisco receiver Bryant Johnson, Matt Maiocco of Instant 49ers reports. Coach Mike Nolan downplayed the injury as a "tweak" even though Johnson spent several minutes on the ground when it happened, Matt Barrows of the Sacramento Bee notes.

Injuries at receiver have made life harder for new coordinator Mike Martz as he installs the offense. A calf injury continues to bother Ashlie Lelie, although he is practicing. Arnaz Battle has also missed time during camp.