HAWTHORN midfielder Liam Shiels could be sidelined for up to a month due to a hamstring strain.

Shiels was substituted out of the Hawks' dominant 62-point Easter Monday win over Geelong early in the third quarter, and scans on Tuesday revealed bad news for the 23-year-old.

"He's had some scans this morning and unfortunately for Liam they're not great," general manager of football operations Chris Fagan told the club's website. "He's got a hamstring strain, so chances are he'll miss three-to-four weeks.

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"No doubt he'll be working pretty hard to get back before then, but that's usually the case with hamstrings so we won't rush him.

"We'll just make sure that he's right when he comes back."

Shiels' injury opens the door for Grant Birchall's return after the veteran defender hurt his knee at training in February.

Fagan said Birchall and premiership backman Matt Spangher (calf) would come under close consideration to face Essendon in round two after their interrupted pre-seasons.

"They didn't play any of our NAB (Challenge) games so we just felt like they needed another week of training and they'll both be available for selection this weekend," Fagan said.

Spangher's spot from last year's premiership team was filled against Geelong by prized free-agency recruit James Frawley. The ex-Demon was a solid contributor with 18 possessions and 11 marks in tough battles with Cats spearheads Tom Hawkins (two goals) and Mitch Clark (three).

"I thought he was fantastic actually," Fagan said. "It was good to see him run and dash with the footy and kick it long.

"He seems to be getting better with each week he plays with the team. It's always a big step up to move from another club where you've played for the last eight or nine years and suddenly fit in somewhere else.

"I think he's doing a really good job."

With a short injury list, the Hawks have a host of players waiting in the wings for a senior opportunity – including ex-Giant Jonathan O'Rourke and Billy Hartung, who were emergencies against Geelong.

Ruckman David Hale is also available for selection for the first time since he pulled up sore from the Hawks' second NAB Challenge match against North Melbourne on March 8. But the 219-game veteran is likely to have to work his way back via the VFL after solid performances from Jonathon Ceglar and Ben McEvoy in round one.

"We just wanted to make sure we had a really fit team coming into round one, so I think ‘Haley’ will be up and about this weekend – probably more maybe at Box Hill, but we'll just wait and see," Fagan said.