San Francisco will be short on reserve running backs for its third preseason game Sunday against the Broncos.
Runners LaMichael James (ankle), Brandon Jacobs (knee) and Jewel Hampton were among the eight 49ers who did not make the trip to Denver. They were joined by wide receivers Joe Hastings and Mario Manningham, linebackers Kourtnei Brown (hamstring) and Darius Fleming and cornerback Chris Culliver.
The injuries to Jacobs and James leave the bulk of the ground work to Frank Gore and Kendall Hunter, although Rock Cartwright should see some significant playing time -- which he may need to get some work on tape if the 49ers release him later this week. Cartwright is currently listed on the fifth string.
Linebacker Aldon Smith did make the trip in spite of a recent hip injury and was warming up in the hours before game time, but whether he plays is still up in the air. He was limited in practice this week. Fellow linebacker NaVorro Bowman was also seen warming up on the field.
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