Reports from Instanbul-based media outlet FutbolArena suggest the midfielder, who has parted company with Melbourne City after three seasons, has agreed to join Super Lig side Yeni Malatyaspor.
Having finished fifth on the ladder last season they have been looking to add depth to their squad and see free agent Brattan as a handy acquisition.
The report states that the 29-year-old is due in Istanbul imminently before heading to the city of Malatya to complete the formalities ahead of the new season.
The about-face is a blow for Sydney who were confident of snaring Brattan to fill the spot created by Josh Brillante’s departure to Melbourne City.
As recently as the weekend indications were that Brattan was on his way to the Harbour City.
It’s understood there was also another last-minute offer from the Korea Republic on the table but Brattan chose Turkey instead in what represents a second crack at making it overseas after his 2016 move to Manchester City ended with an aborted loan to Bolton Wanderers, followed by a swift return to the A-League.
Yeni Malatyaspor are based in the mountainous region of Eastern Anatolia and were only promoted to the top flight in 2017, having been founded in 1986.
They are coached by former Turkey international Sergen Yalcın.