Linebacker Patrick Willis (hamstring) and left tackle Joe Staley (concussion) -- the team's two first-round picks in 2007 -- were not on the field for the start of the 49ers' first practice this week. Running back Frank Gore, however, was going through drills with the rest of the running backs and safety Dashon Goldson (hip) was in uniform and going through drills with the defensive backs.
Willis was working out on a side field with strength coach Mark Uyeyama. He spent time doing squats, moving under and over hurdles and walking with high knee steps. Willis has not yet resumed running full speed, which is perhaps a signal that he will not play in Monday's game. Willis was listed as questionable for Sunday's game against Arizona.
Staley, meanwhile, was kneed in the head on the game against the Cardinals, then collided with a Cardinals linebacker helmet to helmet seven plays later. He walked out of the locker room to join his teammates in practice but has not yet been cleared to participate.
Because of their Monday game, the 49ers have delayed their work week by one game. The Steelers, meanwhile, have been practicing as if it's a normal week.
-- Matt Barrows