Moscow: Top seed Jelena Jankovic went out of the Kremlin Cup at the first hurdle in a 6-1 6-2 thrashing by little-known Kazakh teenager Zarina Diyas on Thursday.
Serbia`s former world number one, who had a bye in the first round, looked out of sorts from the start, committing numerous errors and winning only 43 percent of her first serves. She was beaten in less than an hour by the 268th-ranked Diyas.
"I`m not feeling well. I have been sick since I came from China," said Jankovic, who also suffered a second-round defeat at the China Open earlier this month.
"I got an infection and have been on antibiotics for a week or so and unfortunately I wasn`t ready to play at my level.
"I was suffering a lot but I didn`t want to retire. It was tough for me to focus on my tennis. I had a hard time breathing and I was getting tired quickly and didn`t have much energy."
Jankovic said she would try to recover for next week`s season-ending WTA championships in Doha.
"I just hope that I can recover and feel better for Doha," the world number seven said.
"I`ll see the doctor now and see what I can do. It`s tough, it`s the end of the year, my body is exhausted. It`s been a long season with lots of travelling. I have one more tournament left and hope I can at least be healthy so I can go there and play."
The Kazakh qualifier, who turned 17 three days ago, was as surprised as everyone by her lopsided victory.
"I was very nervous before the match. She is a top player and I have never played someone like her before," Diyas told reporters. "But as the match progressed I started feeling more and more confident and my nerves were gone by the (end of the) first set."
Diyas, who had not won a tour match this year before this week, takes on sixth-seeded Maria Kirilenko in Friday`s quarter-finals after the Russian whitewashed Ukraine`s Kateryna Bondarenko 6-0 6-0 in the earlier match on centre court.
Jankovic became the latest high-profile casualty at the annual ATP and WTA indoor tournament that had been already hit by the withdrawals of top players, particularly on the women`s side.
Russians Vera Zvonareva, Svetlana Kuznetsova and Maria Sharapova as well as Italy`s 2009 champion Francesca Schiavone all pulled out in the run-up to the event.
Men`s top seed Nikolay Davydenko was beaten in his opening match while his Russian compatriot, champion and second seed Mikhail Youzhny, pulled out with a virus on Wednesday.
Third-seeded Frenchman Jo-Wilfried Tsonga, the highest seed left in the men`s draw, faces Serbia`s Viktor Troicki in the last match on centre court later on Thursday.