Mitchell (knee) isn't practicing Wednesday, Matt Maiocco of NBC Sports Bay Area reports.
Mitchell barely played the first two weeks of the season and then suffered a knee injury when he picked up 13 touches in a 30-13 win over the Giants in Week 3. He missed the Week 4 win over Arizona and now appears in danger of missing Sunday's game against Dallas, though a report earlier this week suggested the Niners consider him day-to-day. In any case, lead back Christian McCaffrey is unlikely to come off the field much Sunday in a battle between NFC heavyweights.