SANTA CLARA, Calif. (AP) - San Francisco 49ers running back Jerick McKinnon has left practice with an injured right knee.
The 49ers said Sunday that McKinnon will undergo an MRI to determine the severity of the injury. McKinnon hurt himself about halfway through practice and stayed on the field to watch the finish.
McKinnon signed a $30 million, four-year contract in March. He lost four yards on three carries during his preseason debut, when he played one possession against Dallas on Thursday.
The 49ers already are without backup running back Matt Breida, who is out until the start of the regular season with a shoulder injury. Joe Williams also missed practice because of a death in the family.