THE Round of 16 at both Charleston and Bogota are done and dusted, with plenty of intriguing results coming out of both events.
Charleston saw an intriguing day of results as third seed Petra Kvitova fell to Montenegrin Danka Kovinic and Garbine Muguruza retired in her encounter with fellow seed Yulia Putintseva, unfortunately handing over a dominant first game victory and tight second set to the Kazakh.
Kovinic’s 6-4 6-1 victory over Kvitova was completed in just 76 minutes, with her effectiveness on serve the main kicker, winning points off 69.7 per cent of her first serve compared to Kvitova’s 46.7 per cent, and in arguably one of her biggest wins to-date. For Muguruza, it was a lower leg injury and the quick changeover from hard-court to clay which took a toll and forced her retirement mid-match.
“I was already feeling some pain in my first match,” Muguruza said. “The switch of hard courts to clay was tough, and in a very short amount of time. I started very well, and all of a sudden I felt a sharp pain in my leg, and it got worse. I didn’t want to continue without playing my best tennis. It didn’t make sense to me.”
Also successful on Day 6 were 12th and 14th seeds in Ons Jabeur and Coco Gauff, both reigning supreme under pressure. Tunisian, Jabeur was forced into the only three-setter of the day when she encountered Frenchwoman Alize Cornet, eventually overcoming a first set deficit to claim the 5-7 6-3 6-3 victory in two hours and 40 minutes – far and away the longest match of the day. Meanwhile, Gauff took on compatriot Lauren Davis and came away with a 6-2 7-6(2) victory to stop Davis in her tracks.
A third American in Sloane Stephens joined the winners circle with a 6-3 6-4 dismissal of Australian Ajla Tomljanovic, 6-3 6-4, however things did not go quite as well to plan for compatriot Caty McNally, who fell to Spaniard Paula Badosa in a similar result. The final matches saw Veronika Kudermetova claim a 71-minute 6-0 6-3 victory over Kurumi Nara, whilst the remaining matchup between world number one Ash Barty and a fifth American in Shelby Rogers saw Barty take out the first set tiebreaker before Rogers took out the second set, with Barty just holding on for the 7-6 4-6 6-4 victory under pressure.
VOLVO CAR OPEN ROUND OF 16 RESULTS:
Danka Kovinic (MNE) defeated  Petra Kvitova (CZE) 6-4 6-1
 Yulia Putintseva (KAZ) defeated  Garbine Muguruza (ESP) 0-6 2-2 RET
 Ons Jabeur (TUN) defeated Alize Cornet (FRA) 5-7 6-3 6-3
 Coco Gauff (USA) defeated Lauren Davis (USA) 6-2 7-6
Sloane Stephens (USA) defeated Ajla Tomljanovic (AUS) 6-3 6-4
Paula Badosa (ESP) defeated Caty McNally (USA) 6-3 6-3
Veronika Kudermetova (RUS) defeated Kurumi Nara (JPN) 6-0 6-3
 Ash Barty (AUS) v. Shelby Rogers (USA)
Wildcard Maria Camila Osorio Serrano has continued her dream run on home soil in Bogota, as has qualifier Harmony Tan who reigned supreme in her own Round of 16 encounter. The third winner of the day was fifth seed Slovenian – and only remaining seed – Tamara Zidansek. Zidansek and Osorio Serrano came away with relatively simple victories on the sixth day of proceedings, as the fifth seed disposed of Italian Giulia Gatto-Monticone 6-2 6-3 in one hour and 11 minutes. The Colombian teenage hope in Osorio Serrano completed her maiden Top 100 victory by downing seventh seed Czech Tereza Martincova to head to the quarter finals, requiring just over 90 minutes to claim the 6-3 6-3 victory, with a marginally better serving efficiency allowing her to get the job done. Tan continued the straight sets trend as she disposed of fellow qualifier, Chilean Daniela Seguel in the last match of the day, however required a bit more to overcome her opposition in the 6-4 7-6(3) matchup. Whilst Tan hit seven double faults to Seguel’s two, she was far more effective off her first serve and consistently so in comparison.
COPA COLSANITAS ROUND OF 16 RESULTS:
 Tamara Zidansek (SLO) defeated Giulia Gatto-Monticone (ITA) 6-2 6-3
Maria Camila Osorio Serrano (COL) defeated  Tereza Martincova (CZE) 6-3 6-3
Harmony Tan (FRA) defeated Daniela Seguel (CHI) 6-4 7-6