Lions pair Ryan Harwood and Jono Freeman will have delayed starts to the season, with both to miss up to 12 weeks following surgery.
The Lions have revealed Harwood will have surgery on Monday to alleviate the abdominal and groin pain he has endured in recent weeks.
Freeman, 20, who played four games last season, had a microdiscectomy on a bulging disc in his back on Thursday night and will also miss up to 12 weeks.
"Both Ryan and Jono were disappointed at having to spend time away from the game but we have to do what is best for the players,' Lions football operations manager Dean Warren said.
"They will both come back stronger and the result will be in the best interest of their long-term careers."