Brown (foot) was not spotted at Friday's practice, according to Jamison Hensley of ESPN.com.
Brown popped up on Thursday's injury report with a foot injury, but he was a full participant in practice, so there was not much cause for concern. However, his absence Friday certainly raises an eyebrow and leaves his availability for Week 1 uncertain. The Ravens will provide an official update on Brown's status when their final injury report of the week comes out.