Montenegrin teenager Danka Kovinic continued to impress on her WTA Tour debut at the Hungarian Grand Prix in Budapest.
The 18-year-old followed up her first-round victory over Britain's Johanna Konta by defeating Russia's Valeria Solovyeva 6-1 3-6 6-1 to reach the quarter-finals.
Kovinic came into the tournament in good form after back-to-back titles on the ITF circuit and in the last eight she will meet sixth seed Chanelle Scheepers, who beat Croatia's Petra Martic 7-5 6-4.
Eighth seed Anna Tatishvili was beaten 6-1 6-1 by former top-20 player Shahar Peer, who will play Alexandra Cadantu in the last eight.
The Romanian was 4-0 up in the deciding set against Andrea Hlavackova when the Czech player retired.