Ailing world No. 1 Novak Djokovic decided to pull out of next week's Shanghai Masters event, citing a nagging back injury.
"I did another check this week and the results are not good," Djokovic said. "I need to continue my rehabilitation."
Djokovic overcame the injury en route to capturing his first-ever U.S. Open title last month, but was forced to retire from a Davis Cup match against Argentine slugger Juan Martin del Potro three weeks ago, as his Serbian squad lost to visiting Argentina in a semifinal showdown in Belgrade.
The 24-year-old Djokovic was also forced to pull out of this week's event in Beijing, where he was the two-time reigning champion.
Djokovic ascended to No. 1 for the first time in his career this year, one in which he captured three quarters of the Grand Slam events.