Agnieszka Radwanska became the second high-profile exit at the Porsche Tennis Grand Prix in Stuttgart in as many days after losing out to Sara Errani.
Italian clay specialist Errani dumped out the Polish seventh-seed 7-6 (8/6) 6-4 in a tense match on Wednesday that lasted two hours and eight minutes.
Radwanska's early exit follows just a day after Ana Ivanovic lost to Caroline Garcia for the third time this year.
Errani will now take on Kazakhstan's Zarina Diyas after the 21-year-old rising star dismissed world number 19 Sabine Lisicki 6-0 6-0.
Germany's Angelique Kerber breezed past American Alexa Glatch 6-2 7-5 to set up a second-round meeting with top seed Maria Sharapova.
Source: PA