The star striker could face a race against the clock to be fit and in form for the tournament in Brazil after picking up a muscle problem on club dutyAustralia's World Cup campaign, with a hamstring issue forcing him out of New York Red Bulls' 1-1 draw against Chivas USA.
Cahill, 34, went off in the 27th minute of the Major League Soccer game at Red Bull Arena on Sunday.
"I'd probably get in trouble if I made any statements right now without consulting a doctor, but it looks like at least, the best-case scenario, a strain in the hamstring, worst case scenario a pull in the hamstring," Petke was quoted as saying by BigAppleSoccer.
"But I am going to the doctor now to figure that out."
Australia's World Cup campaign begins against Chile on June 13, giving the veteran forward just over two months to recover.