Top seeds fell on a sizzling first day of match play action on Thursday at the Australian Men's Amateur golf championship as temperatures soared at Commonwealth and Woodlands Golf Clubs in Melbourne.
No.1-seeded West Australian Brady Watt lost 5 and 3 to Anthony Houston of Victoria, while No.2 seed Todd Sinnott and fellow Victorian lost to England's Neil Raymond 4 and 3.
National squad member Cameron Smith endured a tough battle with fellow Queenslander Kade McBride and won on the 19th hole, and Anthony Murdaca of South Australia defeated Victoria's Ryan Laird.
Ryan Ruffels, son of tennis great Ray, defeated Jarryd Felton to make it through to the second round.
In the women's event, world No.1 New Zealander Lydia Ko continued her march towards defending her title with a comfortable 6 and 5 win over Jessica Dengate of NSW in the first round of match play.
It was commanding performance from Ko with birdies on her opening five holes.
Joint top qualifier Grace Lennon lost 2 and 1 to Lauren Hibbert, four-time US mid-amateur champion Meghan Stasi progressed with a 1 up victory over Ellen Davies-Graham of Queensland and Minjee Lee came back from 5 down to defeat Ebony Heard 2 up.
Japan's Asuka Kashiwabara defeated Lauren Sinclair 6 and 4, Hayley Bettencourt defeated Su Hyun-Oh 1 up and Kiwi Julianne Alvarez beat Carly Beck of NSW 3 and 2.
The second and third rounds of match play for men and women will take place on Friday.