Naomi Osaka battled back from 1-5 down in the final set to beat Donna Vekic 6-3, 4-6, 7-6 (7/4) but denied that she was struggling this year.
Kiki Bertens fired eight aces to prevail 7-6 (7/2), 6-4 in one hour 43 minutes to record her first ever win over Donna Vekic.
Both Johanna Konta and Caroline Wozniacki are angling for a maiden Grand Slam title with the winner of their clash on Saturday potentially facing sixth seed Dominika Cibulkova in the Australian Open fourth round and Serena Williams in the quarters.
Donna Vekic (19) was the player Nick Kyrgios was referring to when he jibed at his Swiss opponent Stanislas Wawrinka in a match last week in Montreal. The court microphone caught Kyrgios' comments and the issue became global sports headlines the very next day.
The coach of Donna Vekic is making sure the latest golden girl of women's tennis keeps focused after bursting into the limelight after reaching Sunday's final in Birmingham.
The former world number five from Slovakia showed she still has remarkable resilience as she beat the sensational new girl - Donna Vekic - from Croatia 7-6 (7/5), 6-4.
On her Roland Garros debut last year, likewise as a wildcard entrant, she lost in the opening round to eventual semi-finalist Petra Kvitova but on this occasion her Czech contest had a happy ending against a player better known for her doubles abilities -- Hradecka winning the pairs title in Paris in 2011.
Wozniacki played her 72-minute match during the hottest part of the afternoon when the temperature at Melbourne Park peaked at 106 degrees.