HAWTHORN midfielder Liam Shiels has been ruled out of Thursday night's huge clash with the Sydney Swans and will be out for up to a month because of a hamstring injury. 

Shiels suffered the injury during the second quarter against Port Adelaide last Thursday and the Hawks reported at the time that he was feeling tightness, but scans on the weekend revealed the full extent of the injury.

"We were hopeful for a better result but that's what the scan showed," Hawthorn football general manager Chris Fagan told the club’s website. 

"He's got to do a rehab now and hope he's right in a few weeks time.

Jonathan O'Rourke is firming as the likely replacement for Shiels, with 23 touches in two and a half quarters for Box Hill on Saturday. Mindful of the five-day break between the VFL and AFL, he was rested for the final quarter and a half. 

The Hawks might also consider Will Langford who is back in full training after suffering a punctured lung a fortnight ago. 

Otherwise the news is promising for the ladder leaders. Ruck-forward Jack Fitzpatrick is doing more training as he recovers from concussion that has sidelined him for nearly two months.

Key forward Ryan Schoenmakers has also stepped up his training following a groin injury that has kept him out since round 4, while Matt Spangher is on track for a return to football towards the end of the home and away season following a serious hamstring tear.

The Hawks also expect luckless midfielder Alex Woodward to return next week after suffering a full plantar fascia tear in his comeback game from a third knee reconstruction.