The 49ers started today's practice without their starting defensive line.
Ray McDonald (biceps) and Glenn Dorsey (hamstring) were working on a side field with the team's strength staff while Justin Smith (shoulder) was working on his upper body strength in the weight room. Smith, a 13-year veteran, often gets a day off of practice - as was the case last week - and this could be a trend for the rest of the season.
The silver lining to the injuries is that the team's backups, particularly rookies Quinton Dial and Tank Carradine, will get extra repetitions in practice. Both have recovered from offseason injuries and took part in their first session on Tuesday.
"As much football as possible," Jim Harbaugh said of their workload. "... As many reps as we can get them both with our defense and on the scout-team, 11-on-11 football."
Both players can be elevated to the 53-man roster over the next 20 days. Dial, in fact, could be activated soon if Dorsey is ruled out for Sunday's game against the Titans. If he can't play, Tony Jerod-Eddie would start the game at nose tackle and the Titans certainly would counter with a run-heavy game plan.
Two other players recently eligible to practice, receiver Mario Manningham and cornerback Eric Wright, also were on the field for the start of practice. Wright, Carradine and Dial all were wearing numbers of Titans players, meaning they will work with the scout-team this week.
Guard Alex Boone was working out on a side field at the start of practice. He was listed as questionable with a shoulder injury on last week's injury report but played the whole game.
-- Matt Barrows