McCormack, 31, joins the club a week out from the start of the A-League season. 

The former Leeds, Fulham and Villa forward will be at the club for at least three months.

Fornaroli is expected to be out of action until the new year after suffering an ankle injury in the FFA Cup. 

“I’m here to do a job for the team, support my teammates, work hard for the manager and represent the club in the right manner," McCormack said.

"Hopefully I can show the fans what I can offer the team and I’m very excited about being able to represent this city and its fans at a great club.”

McCormack was a $24 million signing for Villa just over a year ago, but fell out of favour with manager Steve Bruce. 

He had apparently missed several training sessions and was not fit enough to play.

So far this season McCormack has only played a total of 66 minutes across two League Cup fixtures.

He joins the City squad on Monday, pending a medical.