"I have no idea what I did to win except put my heart and soul into every moment on stage, and I think that the crowd might have been able to feel that," Eric Melin told his hometown newspaper, the Lawrence Journal-World, in Lawrence, Kansas.
"Mean Melin" won Friday night with his rendition of the song Hash Pipe by the US band Weezer in Oulu, beating out compatriot Doug "The Thunder" Stroock by 0.2 points.
"Eric Melin is a bit different than the others," said Hanna Jakku, a member of the competition's organizing committee. "He has a clean style: simpler and clearer rock. I also liked that best."
In another twist, Melin advanced to the finals by performing to a song he had composed himself.
His prize was a transparent guitar made from acrylic. About 7,000 people attend the annual event 600 kilometres north of Helsinki.