At Finnvedsvallen, ahead of the record 5010 spectators, Värnamo won against Hammarby with 1-0.
Where Marcus Antonsson became the newcomer's match winner.
Four minutes into the second half, Oscar Johansson found him with a deep lead ball, and Antonsson was safe in the free position where he had a defender against him on each side.
And the striker rolled in his sixth goal of the season, second in the shooting league behind Alexander Jeremejeff on ten goals.
After Antonsson's lead goal, Hammarby never created anything meaningful for a draw.
And Värnamo took their second straight victory in the Allsvenskan, and the club's third in the Allsvenskan debut season.
While Hammarby after the loss is third in the Allsvenskan, the green and whites led before the last round of the spring season.
This week, Hammarby also lost in the final of the Swedish Cup, after penalties against Malmö.