Ana Ivanovic eliminated defending champion Simona Halep from the Dubai Tennis Championship, booking her place in the quarter-finals with a straight-sets victory.
The Serbian beat Daria Gavrilova in under an hour on Tuesday and carried that form into her meeting with the world number three.
Halep began positively, breaking the Serbian – ranked 17th in the world – in her first service game, but play was soon delayed due to light rainfall.
Ivanovic was seen complaining to coach Nigel Sears about the condition of the court once play resumed, but she overcame her concerns, breaking back before taking the first set via a tie-break.
The Serbian continued her impressive showing in the second set, Halep winning just seven points out of a possible 16 from her first serve.
Ivanovic took full advantage by racing to victory in comfortable fashion, triumphing 7-6 (7-2) 6-2.
All of the remaining seeds tumbled later in the day, leaving the competition wide open.
Number two seed Garbine Muguruza was beaten 7-6 (7-3) 6-3 by Elina Svitolina, while third seed Carla Suarez Navarro was eliminated 4-6 6-4 6-3 at the hands of Caroline Garcia in a game hit by a three-hour rain delay.
World number eight and 2013 champion Petra Kvitova stormed into an imposing first-set lead before Madison Brengle – ranked 52 places below her – battled back for a 0-6 7-6 (7-1) 6-3 triumph.
Andrea Petkovic set up a quarter-final clash with Garcia courtesy of a 6-3 6-2 win over Jelena Jankovic, while Coco Vandeweghe built upon her win over 2015 runner-up Karolina Pliskova in the previous round by beating Kristina Mladenovic 7-5 3-6 6-4.
Sara Errani breezed past qualifier Yaroslav Shvedova 6-3 6-0 in under an hour, while Barbora Strycova set up a meeting with Ivanovic after battling from behind to defeat Julia Georges 2-6 6-3 6-1.
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