In cooler, drier conditions under lights at Melbourne Park, Kvitova was dialed-in from the opening point, collecting the first three games before Barty dug into some rallies in the fourth game and benefitted from some Kvitova errors to get on the board at 1-3.
But she would not win another game for the set.
Kvitova’s movement was exceptional; you could hear her rapid little adjustment steps on the Plexicushion as her shoes squeaked into position to unleash her full-flooded groundstrokes.
She belted 12 winners to two on her way to pocketing the first set in under half an hour.
"Petra is absolutely capable of taking a match away from someone. I knew that going in," Barty conceded.
"At times it's very much out of my control, what she does from her end of the court. In the beginning, she served particularly well. Even when I was hitting my spots on first serves, she was returning within a metre or two of the baseline, putting me on the back foot instantly."
"She was clean as a whistle tonight. I have to give all credit to her."
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Barty and the crowd were somewhat stunned, yet the Australian – the first local woman to appear in the Australian Open quarterfinals since Jelena Dokic in 2009 – settled into a groove on serve and began to look more comfortable.
She held her first four service games relatively comfortably as the two women went game for game in a vastly more competitive second set.
Yet Barty’s game unravelled at 4-4; three straight forehand errors handed Kvitova a crucial break.
An ace followed by a forehand winner brought up two match points, and the world No.6 converted on her first when Barty’s backhand return found the net.