St Petersburg, Russia:Marin Cilic rallied to upset top-seeded Nikolay Davydenko 1-6, 7-5, 6-1 on Thursday to advance to the quarterfinals at the St. Petersburg Open.
Davydenko won the first set in 27 minutes, but the fourth-ranked Russian made four double faults in the second set as the 102nd-ranked Cilic leveled the game.
Davydenko, who withdrew from the Madrid Masters last week citing a right elbow injury, made six more double faults in the third set and could only hold his serve in the fifth game.
Davydenko qualified for the season-ending Masters Cup in Shanghai next month by winning the Kremlin Cup two weeks ago.
Earlier on Thursday, third-seeded Mikhail Youzhny beat Mario Ancic 6-4, 6-2, and fourth-seeded Potito Starace defeated qualifier Mikhail Ledovskikh 7-6 (4), 6-2.
Sixth-seeded Fernando Verdasco also reached the quarterfinals, ousting Simone Bolelli 6-4, 6-4.
Youzhny, the 2004 champion, broke Ancic in the third game of the first set and won five consecutive games for a 5-1 lead in the second.
Serving for the match at 5-2, the 19th-ranked Youzhny saved four break points before closing it out on his second match point.
"I played well today. I served well and received well," Youzhny said. "There was a struggle only in the last game on my serve. But before that I held strongly, while there was a struggle on his serve through the entire match."
"He (Youzhny) played a really good match," said Ancic, who missed most of the season because of mononucleosis.
Ancic felt dizzy and weak because of what happened to him this year, which he called normal.