"We're going to have our own party if we succeed in ruining a party and that part is fine by me.
Denmark go into the contest after finishing second in Group D behind England with two wins and a defeat, the same record as Australia, who topped their group.
Having made the last 16 at a World Cup for the first time since 1995, Sondergaard said he is leaving no stone unturned to continue their run.
Australia captain Sam Kerr missed the team's three group stage games due to injury but should be fit for the Denmark clash.
Sondergaard said Australia had shown they were just as good without their talisman, though.
Persons:
Carl Recine, Lars Sondergaard, Monday's, Sondergaard, We've, Sam Kerr, Janni Thomsen, haven't, that's, Thomsen, Shrivathsa Sridhar, Tom Hogue
Organizations:
Soccer Football, FIFA, Sydney Football Stadium, REUTERS, Australia, England, Thomson
Locations:
New Zealand, England, Denmark, Sydney, Australia, Bengaluru