Second seed Yanina Wickmayer was dumped out of the Istanbul Cup at the first attempt on Wednesday as Andreea Mitu recorded a straight-sets win.
After a tight opening set that Mitu just edged, the Romanian turned the screw in the second with a run of five games in six, before serving out for a second-round place.
Next up for Mitu is Stefanie Voegele after she made short work of Ipek Soylu, the Swiss converting eight break chances to win 6-2 7-5.
Also into round two are Kateryna Kozlova and Kirsten Flipkens, the latter edging a first set tie-break before winning six of the final seven games to progress in 7-6 (7-5) 6-4 in 97 minutes.
Meanwhile, world number 127 Maria Sakkari is already into the quarter-finals after seeing off Hsieh Su-wei 6-3 6-4, where she is joined by fifth seed Danka Kovinic - who dispatched Tsevtana Pironkova in straight sets.