Adelaide midfielder Jordan Gallucci has ruptured his Achilles' tendon and will miss the next nine to 12 months.
Crows Head of Science and Medicine Steve Saunders said the 22-year-old sustained the injury in a low-level warm up drill on Friday.
"Scans today have confirmed Jordan has ruptured his left Achilles' tendon and will require surgical reconstruction in the coming days," Saunders said.
"Jordan has had no tendon or lower leg issues at all during the preseason and went into training today with no history of calf/Achilles symptoms over the past couple of years.
"This is obviously devastating for Jordan given it will now require 9-12 months of rehabilitation surgery."