TORONTO (AP) -- Andy Roddick withdrew from the hard-court Rogers Cup tournament Sunday, citing the injury that forced him to pull out of another U.S. Open tuneup last week.
"Unfortunately, my side strain is still preventing me from being able to play matches,'' Roddick said in a statement. "I will be working hard this week and I am optimistic to be back in top form for the U.S. Open.''
He strained the lower left side of his back while playing in an event in Los Angeles last month and pulled out before the quarterfinals. Then he withdrew from the hard-court tournament in Washington.
Roddick, the 2003 U.S. Open champion who has been ranked No. 1, is 10th in the current rankings.
Andre Agassi pulled out of the Rogers Cup on Friday.
The U.S. Open begins Aug. 28.