The club's inaugural coach has sensationally departed only a week before the start of the season to take a managerial role in Turkey.

Western Sydney Wanderers coach Tony Popovic has quit the club to take up a coaching role with Turkish Super Lig side Karabukspor only seven days before the start of the A-League season.

The news broke on Sunday morning - barely 24 hours after Popovic attended the club's family day and posed for photos.

Karabukspor are currenly sitting third-last in Turkey's top flight and Popovic faces a battle to help the club avoid relegation this season.

According to the Daily Telegraph, Popovic had a handshake agreement with Wanderers chairman Paul Lederer to leave the club if the right offer came along.

The 44-year-old departs having won the Asian Champions League in 2014, and also clinching the A-League premiers plate in the club's inaugural season.

However the championship eluded Popovic, with the club losing three A-League grand finals in 2013, 2014 and 2016.

The Wanderers have not yet decided on a replacement ahead of next Sunday's round one clash against Perth Glory, but it's believed assistant coach Ante Milicic will feature in discussions.