Daria Kasatkina upset the odds to progress at the expense of Julia Gorges in the second round of the Nurnberger Gastein Ladies.
Russian qualifier Daria Kasatkina produced a stunning comeback to defeat sixth seed Julia Gorges and maintain her impressive form at the Nurnberger Gastein Ladies.
The world number 151 had already seen off Aleksandra Krunic to reach the second round and was made to fight hard for a 3-6 6-4 6-3 triumph against Gorges.
Kasatkina squandered seven break points in the opening game and eventually lost the first set courtesy of a single break of serve, although Gorges required four set points to go ahead.
Gorges was instantly on the front foot in the second as she opened up a 2-0 advantage, but a resurgent Kasatkina won six of the next eight games to level the match.
And, after striking the first blow in the decisive third set, Kasatkina went on to secure three breaks to two and set up a quarter-final clash with top seed Sara Errani.
Errani also came up against a stubborn qualifier in her second-round clash - eventually beating 133rd-ranked Maryna Zanevska 6-2 4-6 7-5.
Trailing 5-2 in the third set, Errani mustered the willpower to fend off a match point and win five games on the bounce to book her place in the last eight.
"Well, I was winning, 6-2, 2-0, but then I started to miss one thousand balls," said Errani. "She was starting to play much better from there, though.
"It was just a really difficult day for me. But from 5-2 down in the third set I just tried to stay in there, and I'm happy I made it."
Andreea Mitu retired injured when a set down in her match against Anna Karolina Schmiedlova, while Karin Knapp's clash with Johanna Larsson has been postponed until Friday.