On 21 May 2012, it was announced Abbas had signed for Sydney FC on a 2-year deal. Notably a left winger and having spent his entire pre-season playing in that role, Abbas was shifted into the central midfield role by manager Ian Crook early in the 2012–13 season. He scored his first competitive goal for the club against Central Coast Mariners on 3 November 2012 after latching onto the end of a reverse pass by Yairo Yau to volley it over goalkeeper Mathew Ryan.