Kerber survives scare, Mladenovic goes down in a thriller

Top seed Kerber took out the first set but was taken into a third by her Spanish opponent, eventually prevailing 6-2 5-7 7-6 (7-3) at the WTA Premier event.

Kerber, who also knocked out Arruabarrena in Charleston last year on her way to the title, broke twice in the first set and won a total of 76 per cent of points on her first serve.

The German stuttered in the second set as Arruabarrena improved on her serve, but Kerber proved too strong in the third to win after two hours, 39 minutes on clay.

The victory sets up a last-16 clash against the winner of Kateryna Bondarenko and Kristina Kucova.

Mirjana Lucic-Baroni came from behind to clinch a thrilling 4-6 6-4 7-6 (15-13) win over Kristina Mladenovic earlier in the day.

Mladenovic won the first set but Lucic-Baroni battled back before winning a marathon tie-break, saving four match points to move into the second round.

Samantha Stosur set up a last-32 clash against Jana Cepelova after a straight-sets victory over Aleksandra Krunic.

Stosur, the 2010 winner, saved a total of 16 break points on her way to the 6-4 6-4 victory against her Serbian opponent.

In other results, Daria Kasatkina got past Zheng Saisai 6-2 6-1, Eugenie Bouchard dismissed Alexandra Dulgheru 6-3 6-4 and Yulia Putintseva defeated Kurumi Nara 7-6 (7-4) 6-0.

Yaroslava Shvedova secured a 6-1 6-1 win over Evgeniya Rodina, Zhang Shuai eased past Lesley Kerkhove 6-1 6-2 and Louisa Chirico battled past Naomi Osaka 3-6 6-1 6-1.

Monica Puig defeated Lucie Hradecka 6-3 6-2, Kucova beat Madison Brengle 7-5 6-2 and Bethanie Mattek-Sands eliminated Teliana Pereira in a 5-7 6-3 6-2 win.