Bulgarian qualifier Tsvetana Pironkova crushed top seed Vera Zvonareva 6-0, 6-2 in the second round of the Kremlin Cup on Thursday, eliminating the Russian from the season-ending tournament in Doha.
Defeat for the world number seven enabled Serbia's Jelena Jankovic to clinch the last remaining spot in next week's $4.55 million WTA championships regardless of her own progress in Moscow.
Poland's third seed Agnieszka Radwanska, who also had a shot at qualifying for Doha at the start of the week, saw her chances disappear after a first-round defeat by Russia's Maria Kirilenko on Wednesday.
Zvonareva's loss continued the cull of seeds at the annual indoor tournament, celebrating its 20th anniversary this year.
Men's top seed, Nikolay Davydenko was also sent packing by fellow Russian Marat Safin in the first round on Wednesday.
For world number 126 Pironkova it was only her fourth win of the year on the main tour and the first since April.
The 22-year-old will now contest her first quarter-final of the season, where she will meet Ukraine's Alona Bondarenko who knocked out Russia's fifth seed Nadia Petrova on Wednesday.
