A Halmstad that is tempted to avoid a negative qualifying place and an Elfsborg in the battle for top places.
But it was a tough night for the former who had to leave the match without any points.
A penalty save in the 62nd minute and a decisive goal in extra time punished the home team.
The first half did not include any super chances.
The away team's Leo Väisinen had a nod close over the crossbar - but much more than that did not happen in the first 45.
However, more happened in the second act.
After just over an hour of play, Halmstad received a penalty and Simon Kroon stepped forward to take care of it.
Elfsborg goalkeeper Tim Rönning looked focused - and magnificently saved Kroon's penalty when he went in the right direction.
At the end of the match, Rönning would then be in charge of a new parade.
The penalty shooter Kroon came loose and sent off a finish and the goalkeeper saved again.
In overtime, a new blow came for Halmstad.
Jakob Ondrejka entered the penalty area and scored 1-0.
Elfsborg will receive AIK in the next round and Halmstad will be visited by Hammarby.
The text is updated.