He further enhanced his reputation by scoring two goals against Inter Milan in a UEFA Champions League game, a 2–2 home draw;[3] 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.

[6] His volley, which helped the relegation-threatened team earn a crucial 1–1 draw against Bolton Wanderers on 1 February 2006,[7] was both his highlight and only goal of the campaign, in 20 overall appearances.

A 16 June 2006 Norwegian press release reported that Benfica and Brann had agreed on a Karadas transfer back to Bergen.

Only his personal contract was an issue, as the player refused to give up a £350,000 compensation which had to be paid to him whenever he was sold from the Lisbon club.

Karadas made his debut in German football on 27 August 2006 in a 2–0 home league victory over SC Paderborn 07, starting but being substituted in the 61st minute.

His first league goal came 20 days later in a 1–1 draw at SpVgg Unterhaching,[8] his only of the season in an eventual sixth-place finish; he was also sent off after being shown two yellow cards in a local derby against 1.

[20] He returned to the team two years later for a friendly tour of the Middle East, scoring his only goal as a substitute to equalise in a 2–1 win over Oman.

[23] At the end of December 2019, he declined an offer to take up the role as head coach for newly formed Øygarden FK.