49ers RB Christian McCaffrey, LT Trent Williams miss practice

(Photo credit: Sergio Estrada-Imagn Images)

The San Francisco 49ers practiced Tuesday without two key pieces of their offense, running back Christian McCaffrey and left tackle Trent Williams.

They were not mere veterans' rest days. McCaffrey appeared on the injury list with a new back issue, and Williams was listed with the right hamstring injury sustained Sunday night in San Francisco's 42-38 win over the