Moscow (AFP) - Russia's Alisa Kleybanova reached her first WTA quarter-final since she overcame cancer when she beat sixth seeded Spaniard Carla Suarez Navarro 7-6 (7/2), 6-4 in the joint ATP and WTA Kremlin Cup on Wednesday.
The 24-year-old -- winner of two WTA titles -- was once ranked as high as 20th in the world but she has been battling to regain some form ever since she returned to the circuit this year after being treated in 2011 and part of 2012 for Hodgkin's Lymphoma, a form of cancer.
"I always liked to play with Carla and I knew it would be a tough match today," said Kleybanova.
"But I think that today I played more accurately than her at key moments and that's why I won."
Later Italian Roberta Vinci also reached the quarter-finals winning a high quality match with Elena Vesnina of Russia 2-6, 6-1, 6-4.
Vinci, 30 and better known as a double specialist although she is a career high 11th in the singles rankings and seeded two in Moscow, will play another Russian in the last eight in the shape of two-time Grand Slam winner Svetlana Kuznetsova.
Vesnina, 27 and ranked 25th in the world after winning two WTA titles this year, looked in command from the start breaking her rival's serve twice in the opening set to take it in 30 minutes.
But in the second Vinci stepped up a gear breaking her opponent's serve on three occasions -- Vesnina only able to break back once -- to level the match at one set apiece.
The rivals traded breaks early in the third set before Vinci made the decisive break to win the match.
Kuznetsova, seeded eight, advanced into the quarters with a straight-sets win, 6-2, 7-5, over Sofia Arvidsson of Sweden.
Meanwhile, last year's beaten finalist Australia's Samantha Stosur, seeded seven, outclassed unseeded Kaia Kanepi of Estonia, the finalist in 2011, in straight sets 6-3, 6-1 to reach the second round as she was allowed to start her campaign later having jetted in after winning the title in Osaka last Sunday.
The 29-year-old Stosur, ranked 19th to her opponent's 29th, converted four of her 11 break points in the 65-minute encounter to level their head-to-head record at 1-1.
"I played really well today as Kaia is a very dangerous opponent," said Stosur, who is seeking her third title of the year in Moscow.
"I really tried to start the match well. I felt like I played at the same level as in Osaka.
"Last year it was really tough as I had to play too many long matches here.
"Last time I didn't win the final but I have another opportunity here this time around. And so far I did good today and I hope I will carry this for another few days."
Stosur will face Frenchwoman Alize Cornet in the second round.
In the men's section of the event defending champion Andreas Seppi of Italy, who is seeded second, experienced few problems on his way to the quarter-finals, easing past compatriot Paolo Lorenzi 6-3, 6-2.
"It's not easy to play against the guy from your country as we know each other pretty well," Seppi said.
"But I think I played a solid match today with very aggressive tennis. And I think it was a good start to the tournament for me."
Seppi, 29, will face French journeyman Edouard Roger-Vasselin in the quarter-finals, as the latter beat Ukraine's Sergiy Stakhovsky -- conqueror of Roger Federer at Wimbledon this year -- 7-5, 7-5.However, there was an upset as third seed and the 2011 champion Janko Tipsarevic went down to a 6-4, 6-4 defeat by 17-year-old Russian wild card Karen Khachanov, who was playing just his fourth career ATP match.