McMillan is slated to undergo an MRI on his left knee Monday, Jenna Laine of ESPN.com reports.
McMillan missed the Buccaneers' season-opening loss to the Bengals while recovering from a knee injury, then was cleared to play in the Week 2 loss to the Browns but was limited to just seven snaps. He had been expected to play a more substantial role in Sunday's 23-16 loss to the Vikings, but he logged just two snaps before going down with the knee injury on the Buccaneers' first possession and missing the rest of the game. The MRI will provide clarity on the extent of McMillan's latest setback with his knee, but even if imaging reveals nothing overly concerning, the wideout could still be at risk of missing next Sunday's game against the Packers.