After two wins for German Katrin Eckermann on Friday and victory for compatriot Meredith Michaels-Beerbaum a day later, Augustsson stunned the home crowd riding Mic Mac du Tillard.
World number 24 Augustsson, just 26, rode a double clear round with a time of 41.89 seconds in the second round to see off the challenges of Michaels-Beerbaum and another German Carsten-Otto Nagel.
Nagel was riding his best mare Corradina while Michaels-Beerbaum had chosen to ride Unbelievable for the first time in a Grand Prix.
Her decision somewhat paid off as the pair went round without penalties to get within two seconds of Mic Mac.
Behind them lay five more riders who had double clears, albeit all with slower times.
Adopted Ukrainan Katarina Offel withCharlie finished third on the podium, followed by Torben Köhlbrandt, Tim Rieskamp-Goedeking, Lucy Davis and Gert-Jan Bruggink.
Eckermann, who enjoyed such a great start to the week end, did not qualify for the second round after accruing four penalty points.