The Facts: According to ESPN's Adam Schefter, the 49ers said McKinnon will undergo an MRI on his right knee after injuring it today during practice.

Diehards Line: Initial reports from the practice field sounded positive. Matt Maiocco of NBC Sports California reported that McKinnon was hobbling and grabbing behind his right knee. He was checked by the medical staff and he then walked around, watching practice. ... We'll follow up as needed.