Defending champion and No. 2 seed Kiki Bertens beat Russian qualifier Anastasia Potapova 6-4, 7-6 (3) on Friday to move into the semifinals of the St. Petersburg Ladies' Trophy in Russia.
Bertens, the world No. 8, fought back from a 5-2 second-set deficit and also saved three set points in the one-hour, 53-minute match.
The 18-year-old Potapova challenged Bertens throughout, forcing 17 break points. But Bertens, from the Netherlands, fought back, saving all but three of them. Bertens, however, converted four of her six break opportunities.
In the semifinal, she'll face another Russian, Ekaterina Alexandrova, who has won 16 of her past 17 matches.
The first semifinal on Saturday will pit eighth-seeded Elena Rybakina of Kazakhstan against sixth-seeded Maria Sakkari of Greece, who knocked out top seed Belinda Bencic on Friday.
The Swiss breezed through the first set but lost the next two as Sakkari went on to win 2-6, 6-4, 6-3.
Sakkari, ranked No. 21 in the world, had her third win against a top-five player in her career.
Rybakina saved two match points in Set 2 and recovered to beat French qualifier Oceane Dodin 6-7 (5), 7-5, 6-2.
GSB Thailand Open
Japan's Nao Hibino stunned world No. 4 and top seed Elina Svitolina of Ukraine 6-4, 6-2 to reach the semifinals in Hua Hin, Thailand.
It was the first career win against a top 10 player in Hibino's career.
The No. 8 seed, Hibino will meet Leonie Kung of Switzerland, another upset winner. Kung, ranked No. 283 in the world, defeated world No. 27 Qiang Wang of China, the third seed, 7-5, 4-6, 6-4. It was their first-ever meeting.
In the other semifinal, fifth-seeded Magda Linette of Poland will meet play Romania's Patricia Maria Tig after both defeated competitors from China in the quarterfinals.
Linette rebounded from a first-set loss to eliminate Xiyu Wang 2-6, 6-3, 6-3. Tig topped fourth-seeded Saisai Zheng 6-4, 6-2 in 1:41.
--Field Level Media