Ana Ivanovic's hard-court struggles continued at the Luxembourg Open on Thursday as the second seed was beaten by world number 47 Alison van Uytvanck.
Van Uytvanck's 6-4 6-7 (5-7) 7-5 victory in the second round was the third time in the last seven tournaments that Ivanovic has failed to get past the last 16, a run of form that saw her quest for a place at the WTA Finals disappear.
Ivanovic looked out of sorts from the outset as Van Uytvanck applied pressure on the Serb's serve and, although the favourite saved three set points against, eventually she fell behind.
A better second set saw the 27-year-old level in a tie-break and there was little between the pair in the decider, although Ivanovic was having to battle to hold serve.
That resolve faded at a crucial moment in the final game as Van Uytvanck won four successive points to take her place in the last eight, where she will meet Barbora Strycova.
The seventh seed had no such problems in her second-round match as she cast aside Johanna Larsson 6-2 7-5, while fellow seed Jelena Jankovic also won in straight-sets against Anna Tatishvili.
Jankovic broke twice in each set as she cruised to a 6-4 6-2 win in 88 minutes to keep her on course for a third title of 2015.
Thursday's remaining second-round matches saw Stefanie Voegele beat Anna-Lena Friedsam 6-3 7-6 (7-4), while her next opponent Laura Siegemund saw off Kirsten Flipkens 7-6 (7-2) 6-1.