Gustavo Ayon suffered a shoulder injury in the pre-season loss to the Miami Heat on Monday evening.
The 28-year-old injured himself early in the first quarter of the 92-87 defeat after colliding with Miami's Norris Cole and he was immediately helped off the court.
Atlanta have yet to reveal the full extent of the problem as the countdown to the start of the new NBA season continues.
Ayon joined the Hawks as a free agent in the summer following a short spell with the Milawukee Bucks.