Kansas City Chiefs running back Jamaal Charles is day-to-day with a mild strain of his outer right foot.
Trainer Rick Burkholder said Tuesday that two orthopedic surgeons gave independent opinions, ruling out a Lisfranc mid-foot injury or structural issues in the leg or ankle.
"His ankle ligaments were fine," said Burkholder, who came with head coach Andy Reid from Philadelphia. "He had some pain on the outside bone of his foot. We did an X-ray. That was negative. There's a tendon that attaches right at that spot and that's what is sore right now. That's why we call it a strain."
Charles was carted off the field during practice Monday. X-rays taken an hour later were negative. He didn't practice Tuesday and his status for Friday night's preseason game against the San Francisco 49ers is not certain, but Reid told NFL.com, "If he is ready to go, he'll play."
"Special player. Kind of stating the obvious," quarterback Alex Smith said. "Jamaal is a special player but we have to find a way. ... But no question, he'll be missed."
Charles also had a foot injury prior to minicamps in the spring. X-rays for that injury were negative as well. He had left that practice after limping off the field.
Charles rushed for 1,509 yards last season. He missed most of 2011 with a torn ACL. He has rushed for at least 1,000 yards in three of the past four seasons.
Rookie Knile Davis worked with the first team Tuesday. He's competing with second-year player Cyrus Gray and 25-year-old Shane Draughn for reps.