Johnson sustained a strained groin during practice Tuesday, Scott Smith of the Buccaneers' official site reports.
Johnson had to leave practice early Tuesday after picking up the injury. It's unclear at this point how severe the strain is or how long it will keep the second-year wideout sidelined. Any missed time in practice or preseason games could be a big deal for Johnson, as he's jockeying for pecking-order position with the likes of Jalen McMillan (knee) and Ted Hurst in the Bucs' wideout room.