Smith, the son of former Melbourne star, Shaun, suffered a dislocated shoulder after being tackled.
The 21-year-old was taken straight to the rooms and was in obvious discomfort.
Sports medical expert, Doctor Peter Larkins, told 3AW radio, the injury could see him sidelined for as long as three months.
Doc Larkins: "Joel Smith has just dislocated his shoulder. That's potentially three months out." #AFLSaintsDees
— 3AW Football (@3AWisfootball) March 25, 2017