Top seed Davydenko upset in straight sets at China Open
Need the scores from any match played in this or any other tournament? Results
After a three-hour rain delay, it was perhaps unsurprising that the first set was sloppy, with Cilic breaking Davydenko's first service game.
"I don't think it was because of the rain but I didn't play very well," said Davydenko. "I felt very well, I slept for 11 hours and I was fresh ... today I just found it tough to hit the ball."
Davydenko, yet to win a tournament this year after claiming five in 2006, struck back to race to a 3-0 lead in the second set. But Cilic also raised his game and gradually started to get the better of some fine rallies.
The 18-year-old won the next five games to turn the match around and, despite needing treatment on his finger before serving for the match, grabbed his first victory over a top-10 player when Davydenko netted on the first match point.
Davydenko will now head back to Russia for next week's Davis Cup semifinal against Germany before his date with the investigators into betting irregularities surrounding a match he played in Poland at the start of last month.
"I'd have liked to have stayed here longer to prepare mentally for the Davis Cup," Davydenko said.
In the quarterfinals, Cilic will face wild card Nicolas Kiefer, who continued on the comeback trail after a year sidelined by a wrist injury, beating No. 7 seed Jo-Wilfried Tsonga 6-3, 6-4.
MORE TENNIS HEADLINES
- Serena, Djokovic selected as ITF world champs
- Berdych brings on ex-Murray coach Vallverdu
- Indian Aces win inaugural IPTL exhibition event
- All 100 top-ranked men set for Aussie Open