|50/1||Sunderland are 50/1 with Coral to win the Capital One Cup
The Black Cats have paid Goteborg an undisclosed fee for a versatile player who can also play through the middle.
Karlsson, who has represented Sweden at Under-19s international level, made 10 first-team appearances for his old side in 2012-13.
The 5ft 10in attacker previously turned out for IFK Mariestad before joining the Blavitt in 2010.
He made his first senior appearance for the Swedish giants at the age of 17.