Russia's former tennis world number one Dinara Safina will not play again this year because of persistent back pain.
The 25-year-old, who has not played since early May, will miss her third successive grand slam tournament -- the U.S. Open -- after also pulling out of the French Open and Wimbledon.
The Muscovite has sounded pessimistic about her return to the main tour.
Safina has been criticised for reaching the top without winning a grand slam title, losing all three of her major finals (French Open in 2008 and 2009 and 2009 Australian Open).
After missing much of last year, she made a comeback at the Australian Open in January but suffered an embarrassing 6-0 6-0 defeat by Kim Clijsters in the opening round and soon after contemplated quitting the sport.
