After wrapping up the NFC's top seed and earning a first-round playoff bye Sunday, the San Francisco 49ers are still working through how they will deploy their starters in their regular-season finale. But one key player has already been ruled out.

Niners coach Kyle Shanahan said Monday that star running back Christian McCaffrey is dealing with a "mild" strain of his right calf and will not play in Week 18 against the Los Angeles Rams.