UNESCO World Heritage site Budj Bim is under threat as a fire, which started on December 28 by a lightning strike, remains out-of-control.
The fire has grown to 170 hectares in 24 hours.
Heywood incident controller Darren Shiell said tireless efforts today slowed the blaze.
"The lightning struck and ignited the fire almost exactly in the middle of the park," he said.
"We had a direct strategy attack with a large aerial attack as well.
"We had two Helitaks water-bombing and a couple of large air tankers.
"We threw a fair bit at it today."
Mr Shiell expects the blaze will ease as conditions are forecast to improve.
"We had favourable conditions today and are expecting the same overnight," he said.
"We hope these conditions will reduce the fire and even make it non-existent."
Mr Shiell said there was approximately 20 firefighters working on the ground alongside eight air crafts.
Authorities say the fire hasn't damaged any cultural heritage sites.
Keep up-to-date with the latest emergency information through the VicEmergency website via emergency.vic.gov.au/respond/ or the mobile app. If the advice changes to "Watch, Act" put your fire emergency plans into action.
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