Moberg Karlsson's transfer to Sunderland was confirmed earlier this week, and the former IKE Goteburg player is impressed with the club's confidence in his ability.
The 19-year-old told the Shields Gazette: "I will have to be extremely humble. They are extremely good players, and I will be training with players who represent national teams.
"In the beginning I might not be playing, but if that is the case I must not be discouraged because they have given me a four-year contract, which means they believe in me for the future.
"They like my strengths, they like quick, technical players, and that's what they saw in me."
Moberg Karlsson has scored five goals in 11 appearances for Sweden's Under-19 side.