MOSCOW, Russia - Treated on court for difficulty breathing, Jelena Jankovic won't be holding another Kremlin Cup trophy at the end of the week, as the 2008 champion in the Russian capital lost in her opener at the 2010 event.

Watch live tennis from Moscow this week on TennisTV.com!

Jankovic, seeded No.1, lost in just 59 minutes to 17-year-old Kazakh qualifier Zarina Diyas, who is playing just her fifth Sony Ericsson WTA Tour event.

Jankovic is one of eight players who will be competing for season-ending glory at the WTA Championships - Doha 2010, held in Doha, Qatar next week.

"I've been sick since I came from China. I got an infection and have been on antibiotics for a week," Jankovic said. "I wasn't ready to play at my level. I was suffering but didn't want to retire. I finished as well as I could but it was tough to focus on my tennis. I had a hard time breathing and I was getting tired quickly.

"I will see the doctor now. It's the end of the year and my body is exhausted. It has been a long season with lots of travelling. It's one more tournament to go and I hope I can at least be healthy so I can go out there and play the game. I really need to have energy and be able to smile on court and enjoy the game.

"Doha is a different type of tournament because you can lose a match and still win the whole tournament. So anything can happen, but for me the biggest concern is being healthy. We'll see what happens and hopefully I'll be ready."

Check out off-court photos from Moscow now in the gallery!

Diyas' road will only get tougher, as next up she will face No.6 seed Maria Kirilenko, who blanked Kateryna Bondarenko in just 50 minutes, 60 60, her first double bagel in a main draw in her career on the Tour.

Two more Russians snapped up quarterfinal berths. Vera Dushevina beat Elena Vesnina, 64 62, and Anna Chakvetadze beat qualifier Mariya Koryttseva, 61 62. Chakvetadze and Dushevina will play next; Chakvetadze leads the series, 2-0, but the last time they played it was very, very close.

The other two quarterfinals see No.2 seed Victoria Azarenka facing No.7 seed Alisa Kleybanova and No.8 seed María José Martínez Sánchez facing Dominika Cibulkova. All four quarterfinals take the court Friday.