Brattan, 25, left Brisbane Roar over the summer following a contract dispute, and has been training with Manuel Pellegrini's men in a bid to win a contract.
The Hull-born midfielder, who moved over to Australia as a youngster, has impressed with Brisbane Roar - a direct rival of Manchester City's sister club Melbourne City - and now looks set to make his return to England in a surprise deal with City.
However, whilst The Sun report that a deal is close for Brattan, they also add that City are hoping to loan him out almost immediately, and two Championship clubs are in the running.
It's stated that City are considering loaning him to either Bolton Wanderers or Nottingham Forest, before moving him on to affiliate Melbourne City.
Brattan's reputation is constantly growing at the moment, as having starred for Brisbane Roar, he was called up by the Australian national team for the first time in August.
With great passing and the ability to shoot from range, Brattan is seen as somebody who could be something of a late developer - and sending him on loan to a strong Championship side like Forest would be a great litmus test of whether he can handle the step-up in class back in England.