Kuala Lumpur - Russia's Nikolay Davydenko has blamed a wrist injury for his shock first-round defeat at the Malaysian Open on Tuesday.
The world No. 45, who won the tournament in its inaugural year in 2009, said he has been suffering from the injury for some time but ATP rules did not allow him to withdraw.
He lost 6-3, 6-4 to Uruguay's Pablo Cuevas.
Davydenko said he may also face a first-round defeat at the China Open in Beijing next week.
"I'm not feeling good. I have a wrist injury. It will take six, seven or nine weeks to heal. I'm not sure when it will be better," he said.
"I will withdraw from the doubles here.
"Because of the ATP rules, I couldn't pull out. I will take a rest and see how it goes. I will probably go to Beijing and maybe lose in the first round there as well."
World No. 457 Cuevas, who has hardly played in the last two years due to a knee injury, claimed only his second tour victory of the year in his fifth tournament of 2013.
"I've hardly played the last two years because of my knee injuries. That is why I fell to below 1,000 in the world rankings," he said.
"Even this year I didn't play in many tournaments. I played more doubles matches and reached the French Open doubles semi-finals."
Cuevas saved six of seven break points as he defeated former world No. 3 Davydenko in just 84 minutes.
Cuevas will face Ryan Harrison or last week's St. Petersburg Open semi-finalist Joao Sousa later this week.
Results on the second day of the Malaysian Open on Tuesday (x denotes seeds):
Singles first round:
Pablo Cuevas (URU) bt Nikolay Davydenko (RUS) 6-3, 6-4
Pablo Andujar (ESP) bt Grega Zemlja (SLK) 3-6, 7-5, 0-0 (retired)
Vasek Pospisil (CAN x7) bt Victor Hanescu (ROM) 1-6, 6-1, 6-3
Mischa Zverev (GER) bt Horacio Zeballos (ARG) 7-6 (7-5), 6-2