SANTA CLARA -- Left tackle Joe Staley and left guard Mike Iupati did not practice Wednesday because of their sprained knees, but 49ers coach Jim Harbaugh is not yet ruling them out of Sunday's game against Seattle.
Judging from how well Staley and Iupati moved on elliptical machines in the weight room, perhaps there is reason for optimism those Pro Bowl offensive linemen might play.
Then again, Staley sprained the medial collateral ligament in his right knee only three days ago, an injury similar to the one that kept Iupati out of the past two games.
Also out of practice Wednesday -- and seen doing similar cardio work during the media-access window -- were defensive tackle Justin Smith (shoulder) and tight end Vance McDonald (ankle). Smith typically takes Wednesday's off to rest, whereas McDonald is coping with a new injury.
Two key players returned to practice: cornerback Tarell Brown (ribs) in a limited capacity and tight end Garrett Celek, who practiced fully after missing the past two games with a hamstring strain.
Also limited in practice were: running back Frank Gore (ankle), wide receivers Mario Manningham (knee) and Jon Baldwin (calf), defensive tackle Ray McDonald (ankle), and linebacker Dan Skuta (foot).
Fully participating despite injuries were also linebackers NaVorro Bowman (wrist) and Aldon Smith (shoulder).