Melbourne forward Aaron vandenBerg will miss the start of the home and away season due to a stress fracture in his foot.
The 25-year-old will not require surgery, but will miss up to six weeks.
"Aaron presented with a sore heel over the weekend," Demons football manager Mahoney said.
"Investigations have shown that he has the early stages of a stress fracture.
"We're taking the opportunity to get on top of that as early as we can. He'll have a couple of weeks of 'de-loading' and we'll gradually build him up.
"At this stage we're looking at a timeline of four-to-six weeks until he's ready to return to play."
Meanwhile, defender Sam Frost is also racing the clock to be fit for round one with a toe injury.
The Demons take on St Kilda at Etihad Stadium in round one.