King edged Errani 2-6, 6-6 (9-7), 6-3 in a second-round match that took 2 hours, 41 minutes to complete. Errani actually won more points (115-113) but that was because of an advantage built up in the first set.
Errani fought off 6-of-7 break points while converting all of her break chances in taking the first set. King kept Errani on the defensive from there, however, forcing seven more break chances in each of the next two sets and finishing off a total of five of them.
Two of her six breaks came in the final set,
No. 1 seed and defending champion Li Na had five breaks in a 6-1, 6-4 win over Nadiya Kichenok, claiming 52 percent of the points off Kichenok's serve.
Patricia Mayr-Achleitner took out third-seeded Klara Zakopalova 7-6 (7-2), 6-4 by getting the lone break of the second set and Barbora Zahlavova Strycova was able to finish off a 6-0, 7-6 (8-6) upset of No. 7-seeded Zheng Jie while No. 8-seedd Annika Beck stopped Viktorija Golubic 6-3, 5-7, 6-3.
Also Wednesday, Monica Niculescu outlasted Chan Yung-Jan 2-6, 6-3, 6-0 and Jana Cepelova beat Anna-Lena Friedsam 6-4, 6-1.
Li will go against Niculescu while Mayr-Achleitner meets Beck in the quarterfinals. Fifth-seeded Peng Shuai draws Cepelova and King faces Zahlavova Strycova in the other quarters.