Russia's Vera Zvonareva stunned sixth seeded Amelie Mauresmo 4-6, 6-3, 6-4 to advance to the second round of the Kremlin Cup on Wednesday with her first ever victory over the Frenchwoman.
After battling for over two hours, unseeded Zvonareva scored a decisive break in the ninth game of the third set before clinching the win on her first opportunity when the 11th-ranked Frenchwoman hit a wild backhand on match point.
It was Zvonareva's first victory over the former world number one following seven straight defeats.
"Finally I was able to beat her, it feels great," the 24th-ranked Muscovite told reporters.
Zvonareva's reward for defeating the Frenchwoman is a match against rising Polish teenager Agnieszka Radwanska, who beat Russia's Maria Kirilenko in the first round.
In the men's draw, Mauresmo's compatriot Paul-Henri Mathieu fared much better.
The fourth seed, who won his first career title in Moscow five years ago, became the first player on the men's side to reach the quarter-finals with a straight-forward 6-3, 6-4 win over Russian wildcard Igor Kunitsyn.
Later on Wednesday, top women's seed Svetlana Kuznetsova faces Argentina's Gisela Dulko while second seed and fellow Russian Maria Sharapova meets Belarussian teenager Victoria Azarenka.
Britain's third seed Andy Murray is also in action as he makes his Moscow debut against Russian teenager Evgeny Korolev.