Daria Gavrilova's Kremlin Cup campaign has came to an end at the hands of Britain's Johanna Konta in the round of 16.
Gavrilova, a former finalist at this event in 2016, went down 6-4 3-3 6-3 to the Sydney-born Konta on Wednesday in the Russian capital.
Former world No.1 Karolina Pliskova was stunned 6-1 6-2 by qualifier Vera Zvonareva, but defeat came with a silver lining for the Czech who secured qualification for the WTA Finals
Pliskova's loss meant Elina Svitolina booked her place in next week's season-ending tournament in Singapore.
However, fellow contender Kiki Bertens lost in three sets to Aliaksandra Sasnovich to give Pliskova the eighth and final spot.
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"I'm delighted to be appearing at the WTA Finals for the third time," world No.5 Pliskova said.
"I have such great memories from playing in Singapore in 2016 and 2017, and I can't wait to close out the year competing against the other elite players of 2018."
Russian Zvonareva raced into a 4-0 lead in the opening set and the 34-year-old continued her dominance in the second set to seal her first win over a top-10 player since 2011. She next faces fifth seed Anastasija Sevastova.
Sasnovich overcame a mid-match lapse to dump out fourth seed Bertens 6-3 4-6 6-3 and the Dutchwoman is now the first alternate for the WTA finals.
Former US Open champion Sloane Stephens, another player who will feature in Singapore, made a slew of errors in her 6-3 6-2 defeat by Tunisia's Ons Jabeur.
