Svetlana Kuznetsova dumped last year's runner-up Mihaela Buzarnescu out of the Prague Open on Tuesday with a straight-sets victory.
Buzarnescu, the world number 29, was meeting Kuznetsova for the first time and the fourth seed came undone at the hands of the two-time grand slam champion in an hour and 25 minutes.
Kuznetsova won 76 per cent of points on her first serve and was broken only once in a 6-4 6-2 success in which she broke Buzarnescu four times.
Second seed Anastasija Sevastova lost in three sets to Anastasia Potapova and fifth seed Danielle Collins succumbed to American compatriot Jennifer Brady in a match that also went the distance.
Wang Qiang avoided a surprise exit, the third seed coming through 6-3 3-6 6-2 against Margarita Gasparyan after two hours and 15 minutes.
Viktoria Kuzmova, seeded seventh, bowed out in the first round as she lost 6-3 6-3 to Anna Karolina Schmiedlova. There was better fortune for sixth seed Katerina Siniakova and ninth seed Barbora Strycova, who claimed straight-sets wins over Dalila Jakupovic and 2017 champion Monam Barthel respectively.
Defending champion Elise Mertens, top seed and the only top-20 player in the draw at the Grand Prix de Sar la Princesse Lalla Meryem, needed just over an hour to dispatch Belgian countrywoman Kirsten Flipkens 6-3 6-1.
Johanna Konta, the seventh seed, saved three match points in a remarkable comeback against Wang Yafan. She trailed 6-4 6-5 and fell 0-40 down, only to win 12 straight points to win a tie-break and force a decider that she claimed to progress 4-6 7-6 (7-0) 6-4.
Second seed Hsieh Su-wei was victorious in a three-set contest with Daria Gavrilova, 2018 runner-up Ajla Tomljanovic beat Fiona Ferro in straight sets and Maria Sakkari dropped only two games against Olga Danilovic in Rabat.
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