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The second seed only scraped through to the third round by the skin of her teeth, saving two match points at 5-1 down in the third set against 119th ranked Jana Fett.
But on Friday she gave her most assured performance of the tournament so far, cruising past Kiki Bertens of the Netherlands 6-4, 6-3 in an hour and 26 minutes.
She next faces 19th seed Magdalena Rybarikova of Slovakia for a place in the quarter-finals.