Johnson sustained a rib injury during Sunday's divisional-round game against the Rams, Carmen Vitali of the Buccaneers' official site reports.
Before he exited in the second half, Johnson gathered in three of six targets for 15 yards. With the second-year wide receiver sidelined, Cyril Grayson (hamstring) and Breshad Perriman (hip) inactive and Chris Godwin (knee) on injured reserve, the Buccaneers are down to Mike Evans, Scotty Miller and John Brown at the position.