26-year old RB Michael Bush has a broken thumb which could sideline him for the start of the season.  Bush has played in 3 games this pre-season for the Raiders and he carried the ball 22 times for 80 yards (3.6 ypc) with 1 TD run.  He also caught 4 passes for 47 yards (11.8 avg) during the pre-season.  Bush was in line to be the primary ball carrier for the Raiders as this pre-season came right behind a solid 2009.  Bush played in 16 games (7 starts) for the Raiders last year and he carried the ball 123 times for 589 yards (4.8 ypc) with 3 TD runs.  He also caught 17 passes for 105 yards (6.2 avg) last year.  The Raiders hope Bush is ready to return to action soon.