Djurgarden were using the match to mark their 135th anniversary, and it turned into quite the celebration by thumping Vasteras, taking their unbeaten run to five and denying Gronvitt a five-game unbeaten streak of their own.
The party begin in the fifth minute when Kristian Lien squared to Patric Aslund, who fired into the roof of the net to open the scoring, before Lien turned from provider to scorer eight minutes later when he struck on the rebound after Oskar Fallenius' shot came back off the post.
A Max Larsson corner was met by a firm Adam Stahl header in the 28th minute that gave the goalkeeper no chance, before Djurgarden added three more in a seven-minute spell in the second half.
A long ball forward allowed Bo Hegland to beat the offside line and square for Lien to tap in his second, before the striker completed his hat-trick in the 55th minute, when Aslund won the ball back in the Vasteras half and Lien powered the ball into the top corner. Miro Tenho made it 6-0 on the hour mark, heading in a Hegland cross following a corner routine.
Vasteras were grateful that the goals finally dried up, though their worsened goal difference meant they dropped a place to seventh. Such was the visitors' form before this match, it would have been them overhauling Hacken and moving into third place with a win, but instead that went to Blaranderna.
Sirius have reached the halfway mark in the season still unbeaten and - after Hammarby could only draw against Brommapojkarna - went 14 points clear at the top of the table by beating Halmstad, who stay bottom of the pile and nine points from guaranteed safety.
The two goals arrived within two minutes of each other in the first 16 minutes of the game. The first came from a corner taken short to Marcus Lindberg, whose cross was flicked on by a defender but only to Tobias Anker, who met it at the back post and headed in.
Halmstad looked to be in for a long evening when Ludvig Arvidsson brought down Robbie Ure inside the area just seconds later, and Isak Bjerkebo sent the goalkeeper the wrong way from the penalty spot.
But credit to the strugglers, they created chances of their own but just couldn't find a route back into the match, while they kept the score respectable at the other end, despite the best efforts of Ure and Bjerkebo either side of the break.
The win takes Sirius to 41 points after 15 matches, two points more than they managed in twice as many games last season. Halmstad return to losing ways after drawing with GAIS last time, and are now winless in six.
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