49ers' Christian McCaffrey Sidelined with Calf Injury

San Francisco's star running back will miss preseason, expected to return before regular season opener.

Christian McCaffrey has a calf strain, sidelining him for several weeks of practice.
McCaffrey will not participate in any preseason games to ensure full recovery.
Backup RB Elijah Mitchell is also out with a hamstring strain, prompting the 49ers to sign Matt Breida.
McCaffrey's injury adds to the 49ers' preseason challenges, including contract issues with key players.
Despite the injury, McCaffrey is anticipated to be ready for the season opener on September 9.