Top seeds Anastasija Sevastova and Mihaela Buzarnescu both won in straight sets on Wednesday to reach the last eight of the Bucharest Open.

Sevastova was on court for one hour and 23 minutes in her 6-1 7-5 victory over Arantxa Rus, who was broken five times by her Latvian opponent.

Romanian Buzarnescu - who is seeded second for the tournament in her homeland - rallied from a 4-1 deficit in the second set to triumph 6-3 7-5 against Tamara Zidansek.

Her reward is a quarter-final clash with Wang Yafan of China, who had won the first set against seventh seed Pauline Parmentier via a tie-break and was 3-0 up in the second when her French opponent retired.

Polona Hercog progressed at the expense of Irina Bara, the eighth seed producing a 7-5 6-2 result.

At the Ladies Championship Gstaad in Switzerland, second seed Johanna Larsson saw off Wimbledon junior finalist Leonie Kung.

Teenager Kung - making her main draw debut on the WTA Tour - stood toe-to-toe with the Swede in an absorbing opening set before Larsson's class came through, allowing her to record a 6-4 6-1 victory.

"I was a little bit lucky - she played doubles yesterday so I was able to watch a little bit," Larsson said. "Otherwise I didn't even have a face to put to this girl!"

Stefanie Voegele was on the wrong end of an upset, the seventh seed managing just two games in her clash with Germany's Tamara Korpatsch, while Evgeniya Rodina came out on top in a three-set tussle with Mona Barthel.