“I wish I would be like that a few years ago. Finally, I understand what everyone was looking for and asking for ... I need to be a little bit boring on court,” she said.

“I’m just trying to stay away from negative [emotions] and just fight for every point. There were a few moments when I was about to throw my racquet or scream something.”

Sabalenka conceded she struggled with nerves in the second week of last year’s Australian Open, when she lost in an upset to Estonian Kaia Kenepi in the fourth round. “I remember I was getting nervous, over-thinking, over-dreaming,” she said.

The Belarusian’s first-serve percentage dropped back down to 52 per cent in the second set, but she clipped one at 193 km/h and was the superior returner and ball striker throughout, hitting 32 winners to Mertens’ 12.

Meanwhile, on Saturday, China’s Zhang Shuai ended the surprise run of American qualifier Katie Volynets, who had knocked out ninth seed Veronika Kudermetova in the previous round but was no match for the dominant Zhang.

China’s top-ranked player needed only an hour to get past Volynets 6-3, 6-2 and book a place against big-serving Czech Karolina Pliskova in round four – before heading back out on court for the doubles later on Saturday.

Pliskova, the 30th seed, made light work of 97th-ranked Varvara Gracheva of Russia, triumphing 6-4, 6-2 just after midday. And Croatian fan favourite Donna Vekic easily defeated Spain’s Nuria Parrizas-Diaz 6-2, 6-2 in an hour-long session on Margaret Court Arena.

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Fourth seed Caroline Garcia needed three sets to overcome Laura Siegemund after being steamrolled by the German veteran in the opening set. Garcia upped her service game in the second set, lifting her first serve percentage to 77 per cent from 56 per cent, and winning three in four points when it landed.

After her strong start, Seigemund’s level dropped, allowing the French Garcia to prevail 1-6, 6-3, 6-3.

But the favourite failed to prevail in a Czech on Czech battle between Marketa Vondrousova and the youngest woman remaining in the draw, Linda Fruhvirtova. The 17-year-old won five straight games to come back from 1-3 down in the decider and book a place against Vekic in the round of 16 with a 7-5, 2-6, 6-3 win.

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