Jonathan O'Rourke is the most likely candidate to replace Liam Shiels in Hawthorn's team for the AFL blockbuster against Sydney.
Shiels sat out the second half of last week's win over Port Adelaide and the Hawks were hopeful it was only hamstring soreness.
But the scans were worse than expected and the three-time premiership midfielder will be out of action for three to four weeks.
O'Rourke played in the first three rounds this season, but has been out of the senior side since.
The former GWS player impressed in the first half for VFL affiliates Box Hill last weekend, but sat out most of the rest of the match.
There is only a five-day gap between that VFL match and Thursday's night big game at the SCG.
Sydney are also set to make a change, with young star Isaac Heeney a big chance to be recalled.
Heeney was rested from last Friday night's outstanding win in Geelong over the Cats, but he trained on Tuesday.
Swans midfielder Ben McGlynn responded to his axing from the senior team with 25 disposals and two goals.
Hawthorn have won their last six matches to take top spot as they aim for a fourth-straight premiership.
The Swans are second, one game below Hawthorn and with a much better percentage.
Sydney beat Hawthorn by 14 points in round nine at the MCG - the last time the Hawks lost.