Russia's Ekaterina Makarova stunned seventh seed Agnieszka Radwanska in the first round of the Porsche Tennis Grand Prix in Stuttgart on Tuesday.
The world number 43 triumphed 6-2 6-4 against the Polish former Wimbledon finalist, and will play fellow Russian Maria Sharapova in round two if the former world number one progresses as she makes a controversial return from a 15-month doping suspension.
Sharapova - a wild-card entry for the tournament - will face Italy's Roberta Vinci in the first round on Wednesday.
Earlier on Tuesday, Barbora Strycova set up a second-round match against world number five Simona Halep by beating American Jennifer Brady 6-2 6-2.
Eighth seed Svetlana Kuznetsova of Russia defeated Holland's Kiki Bertens 6-3 5-7 6-3 and will next take on German wild card Laura Siegemund, who saw off China's Shuai Zhang 6-2 7-6 (7/4).
Estonian Anett Kontaveit beat Croatia's Ana Konjuh 7-6 (7/5) 6-4 to book a second-round date with Spain's world number six Garbine Muguruza.
At the Istanbul Cup in Turkey, third seed Irina-Camelia Begu came from behind to defeat German Tatjana Maria 1-6 6-1 7-5.
Sorana Cirstea, who along with Begu helped Romania to a Fed Cup victory over Great Britain at the weekend, also advanced to round two. The fifth seed overcame Fiona Ferro of France 6-3 6-1.
Fourth seed Eugenie Bouchard was ousted, though, Slovakia's Jana Cepelova toppling the Canadian 6-0 6-4.
And Tsvetana Pironkova, the seventh seed from Bulgaria, was also knocked out, with home player Basak Eraydin prevailing 6-2 6-4.
Source: PA
