'S-HERTOGENBOSCH, The Netherlands - World No.161 Antonia Lottner shocked top seed Dominika Cibulkova by knocking her out of the Ricoh Open, 7-5, 2-6, 6-4.
The World No.6 struggled with her serve, and the 20-year-old German took full advantage, pushing her all the way to take her first main draw win of the year.
Cibulkova had set point at 5-4 in the first, but the brave Lottner held her nerve - and her serve - to save it.
And it was Lottner who edged the first set in the end, breaking the Slovakian's serve and then holding to take it 7-5.
The decider was tight and dramatic, with the pair exchanging breaks of serve, but it was Lottner who won the race to serve it out, taking her first match point to wrap up a dramatic upset win.
Next up for her will be Evgeniya Rodina, who beat Miyu Kato 6-1, 6-1 in their first-round clash.
Elsewhere, former champion Camila Giorgi fell to Carina Witthoeft 7-6, 6-3; Natalia Vikhlyantseva beat Andrea Petkovic 6-3, 5-7, 6-2; and Lesia Tsurenko beat wildcard Petra Krejsova 6-2, 6-3.