Mudadana was content with his two-under 69 in a windy opening round at Te Arai Links, 100km north of Auckland, in New Zealand.
But the 20-year-old and the rest of the field are chasing reigning champ Fifa Laopakdee, who fired a stunning eight-under 63 on Thursday.
Australia's top-ranked amateur, and the top-ranked golfer in the field, Harry Tikas carded one under in a tournament carrying a coveted prize: the winner secures a berth at next year's US Masters and British Open.
Mudadana was among the leaders at four under and blemish-free until striking trouble on his 17th hole - the par-3 eighth - leading to a double-bogey.
The Australian missed the green and copped a tough lie, forcing him to chip sideways.
"I wasn't really in any danger all day," Mudadana said.
"But on eight, I pulled a pretty bad lie and had no real options. Just a bit of bad luck.
"I played pretty well. It's not the easiest day out there with all sorts of conditions ... I can't complain, it was a solid round."
In winds of 45km/h, compatriot Takis banked consecutive birdies followed by an eagle to be four under through seven holes.
But his putter then faltered, with a trio of three-putts marring his round.
"I putted really good the front nine, made a few really long ones and didn't really miss anything," Takis said.
"And then I really struggled.
"When the greens get this baked out, there's not much grass on them, and when you get a gust downwind you feel like you can tap it and it'll go 20 feet, so that was a big struggle."
Behind pacesetter Laopakdee are New Zealanders Joshua Bai (66), Ryan Xie and Cooper Moore (both 67).
Mudadana and Takis were the only Australians under par, with Wesley Hinton even, Harrison Gomez, Sam Cascio and Jonty Lunson all two over, 58-year-old Graham Hourn eight over and Rick Heath 12 over.
Meanwhile, tournament organisers announced venues for the next two years, with Hoiana Shores Golf Club in Hoi An, Vietnam, to host next year, followed by Sydney's New South Wales Golf Club in 2028.
This article was made possible with support from the Asia-Pacific Amateur Championship.
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