Ukrainian teenager Dayana Yastremska reached the quarter-finals of the Adelaide International after her opponent Angelique Kerber was forced to withdraw with a hamstring injury.
Yastremska had won the first set 6-3 against the German ninth seed and broke to lead 2-0 in the second before Kerber signalled that she could not continue.
Fourth seed Belinda Bencic, who entered the tournament as a wild card, also progressed via two close tie-break sets over Julia Goerges, 7-6 (6) 7-6 (4).
Eighth seed Marketa Vondrousova needed just 51 minutes to pull off a rare ‘double-bagel’ 6-0 6-0 victory over Australia’s Arina Rodionova.
Fifth seed Aryna Sabalenka defeated American Bernarda Pera 7-6 (4) 6-2, and there were also wins for Donna Vekic and Danielle Collins, who beat Maria Sakkari and seventh seed Sofia Kenin respectively.
Garbine Muguruza survived from match point down to edge past Tunisian qualifier Ons Jabeur 6-3 3-6 7-6 (4) in two hours and 23 minutes.
In a rain-affected match, Muguruza let slip an early advantage in the final set and a double-fault gave Jabeur a solitary match point at 5-6, before the Spaniard clawed back to win.
Top seed Elise Mertens had a much easier time as she breezed past Viktoria Kuzmova 6-1 6-0 to set up a last eight meeting with Britain’s Heather Watson, a 7-6 (5) 6-3 winner over Fiona Ferro of France.
Third seed Elena Rybakina beat Alize Cornet 7-5 6-3 and will next face local wild card Lizette Cabrera, who continued to delight home fans with a 4-6 6-4 6-4 win over Kristyna Pliskova.
American Lauren Davis beat sixth seed Magda Linette 6-4 6-4 and there were also wins for fourth seed Shuai Zhang and fifth seed Veronika Kudermetova.
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