St Kilda rookie Jack Sinclair could find himself back on the senior list with Tom Curren requiring surgery on a broken ankle.
Sinclair impressed in his 10 AFL games this season but went back on the rookie list last week with the Saints opting to elevate veteran Adam Schneider as the mid-season nominated rookie.
Under AFL rules, the only way for Sinclair to play senior football again this season was if another Saint was placed on the long-term injury list.
Curren broke his ankle during Sunday's VFL win over Footscray, while Blake Acres also suffered a broken hand during the game and is expected to be out for two to three weeks.
Curren's prognosis is more serious with the 22-year-old midfielder sidelined for up to three months.
"He's having surgery and we expect him to miss 10 to 12 week," Saints physiotherapist Andrew Wallis told saints.com.au.
The club is yet to decide whether to place Curren on the long-term injury list while St Kilda coach Alan Richardson said American Jason Holmes and Ahmed Saad were also possibilities after good VFL performances.
Saints duo Jack Billings (shin soreness) and Sam Fisher (back) look almost certain to be available for selection against Essendon on Sunday at Etihad Stadium.
Veteran Fisher was a late withdrawal from their six-point loss to the Western Bulldogs following back tightness on game day.
"We expect Sam and Jack to be available providing they get through training later this week," Wallis said.