Sydney FC locked up another piece of their A-League future with the re-signing of exciting young midfielder Dimitri Petratos on Thursday.The 18-year-old signed a new deal that will tie him to the Sky Blues for a further two seasons.Petratos has played an integral part in struggling defending champion Sydney FC's late season revival, scoring a wonderful goal in last weekend's 2-0 victory over Gold Coast."It's been a big challenge adjusting to the speed and physicality of the A-League but it is something I am enjoying," he said."I am learning every day and with every game."Petratos joins a host of young talent locked up at the club, including 19-year-olds Rhyan Grant and Kofi Danning, 21-year-old Sebastian Ryall, 22-year-old Scott Jamieson and injured 17-year-old Terry Antonis.