Magdalena Rybarikova cruised to a 6-2 6-2 victory over Daria Kasatkina to set up a second-round clash with top seed Simona Halep at the Stuttgart Open.
Halep and Garbine Muguruza were given first-round byes at the WTA Premier event and the Romanian will now face 2017 Wimbledon semi-finalist Rybarikova – the winner of Monday's only main-draw match.
There were two matches played at the Istanbul Cup, where second seed Svetlana Kuznetsova progressed in straight sets.
The Russian was a 6-3 6-3 winner against Wang Qiang – her first victory since the US Open due to a wrist injury – while Christina McHale battled past Mona Barthel.
In a tight contest, McHale prevailed 7-6 (7-4) 4-6 6-3.