Jaiden Hunter ruptures his ACL and is set to miss the 2024 season.
"Jaiden has worked extremely hard over the pre-season to return to full training following an injury interrupted end to 2023, so we are all extremely disappointed for him," Essendon general manager of AFL Daniel McPherson said.
"The incident occurred in an innocuous marking contest during match simulation, where Jaiden was then assisted from the ground.
"Jaiden will undergo surgery in due course, and everyone at Essendon will be fully behind him as he commences his rehab journey."