[1] Having gone through all age groups in Red Star Belgrade youth setup, 18-year-old Janković earned his first taste of full squad action throughout fall 2002, during first half of 2002–03 season under head coach Zoran Filipović.

However, over the winter 2002–03 break in January 2003, Janković was loaned out to lower division side Jedinstvo Ub along with Dušan Basta and Aleksandar Luković in order to gain valuable experience through regular playing time.

[2] All the success prompted new head coach Ljupko Petrović and the rest in Red Star management to bring Janković back during summer 2004, ahead of the 2004–05 season.

The move paid immediate dividends as he scored a spectacular free kick goal versus PSV Eindhoven in the first leg of UEFA Champions League third qualifying round.

He followed that up with a notable domestic season in which he scored 10 goals in 25 appearances, showing early signs of the things to come and establishing himself as one of the more important players on the league winning Red Star roster.

Janković truly came into his own throughout the 2005–06 season under head coach Walter Zenga, increasing his league scoring output to 12 goals in 26 appearances while also providing steady service from the right wing to Red Star strikers, most notably Nikola Žigić.