Karadas was born in Nordfjordeid of Turkish origin, his surname meaning “Black stone” in Turkish. He started his career with Eid IL, moving to the professionals in 1999 with SK Brann. On 13 March 2002, Karadas signed for Rosenborg BK, reportedly receiving death threats over this move. At his new club, his performances soon earned him a call-up to the Norwegian under-21s, and it was not long before foreign eyes focused on the him. He further enhanced his reputation by scoring two goals against Inter Milan in a UEFA Champions League game, a 2–2 home draw; he was linked with the likes of Roda JC, Liverpool and Udinese Calcio, but Portuguese club S.L. Benfica eventually bought the 23-year-old, and he joined the squad of veteran coach Giovanni Trapattoni after signing a four-year contract.