X-rays on Brown's ankle came back negative, but he had a walking boot on his left foot after Sunday's 19-9 loss to the Seahawks, Darren Urban of the Cardinals' official site reports.
While Brown didn't break any bones, the boot suggests he may have suffered ligament damage. A high ankle sprain could mean a 4-to-6-week absence for Brown, who caught five of nine targets for 68 yards before getting hurt. Even recovering from a milder low ankle sprain would be an uphill battle before Thursday's Week 7 clash with the Saints, but at least Arizona's expected to get fellow wide receiver DeAndre Hopkins back from suspension for that one.