Essendon duo Cale Hooker and David Zaharakis have both suffered injury setbacks.
Hooker is still feeling pain in his hip after undergoing post-season surgery.
“Cale finished the season with some hip pain. We felt that with an extended period of rest over the off-season, this pain would go,” Bombers head of medical services David Rundle told essendonfc.com.au.
“But unfortunately, after a few weeks of running, the hip pain was still there and probably getting a bit worse.
“We sought specialist opinion and he underwent an arthroscopy yesterday – a relatively minor procedure – and we should see him back up and running in the new year.”
Zaharakis's will undergo surgery on Thursday to repair a minor meniscus tear in his right knee.
“David had ankle surgery in the off-season, he was rehabilitating really well following that and his ankle was feeling great," Rundle said.
“Unfortunately, after a couple of weeks of running, his right knee had some swelling and clicking in it and he was found to have a small meniscus tear. He’s undergoing an arthroscopy today.”
Essendon youngster Noah Gown has re-fractured a bone in his foot and will see a specialist on Friday.