Jade Culph's hopes of a third Margaret Court Cup have been crushed by young gun Leon Hemmings.
Culph lost the opening set 7-5 as little separated the pair.
But Hemmings found another gear in the second set as he posted a commanding 6-2 win to advance to the quarter-finals.
Hemmings who is seeded fourth will now face fifth seed Taj Hibbert in the quarter-final to be played on Monday.
Culph was seeded 13th in the tournament.
In other quarter final match-ups top seed Blazo Djurovic will play Jack Swindells.
Cooper Wilkinson and Pedro Papangelis will face off as will Aitor Lasa and Matthew Scheers.
The women's open singles semi-finals are scheduled for Monday.
Unseeded Ashley Katz caused one of the biggest upsets of the tournament in the quarter-final after she claimed the prized scalp on top seed Ashley Simes.
In a thrilling encounter Katz lost the first set in a tie-break before claiming the second set 6-3.
Katz held her nerve in a tense third set to win 11-9 in one of the matches of the tournament.
She will now face Taya Powell for the right to advance to the final.
Baihe Lin and Sarah Munroe will clash in the other semi-final.
Several finals for the junior grades will be held on Monday with the remaining finals held the following day.
Organisers will be hoping to beat the heat with the the forecast of a heatwave for most of this week with temperatures close to 40 degrees.