Anna Kournikova's agent has admitted it is unlikely that the Russian will ever return to top level tennis.
Kournikova has been reduced to playing exhibition doubles
The 22-year-old has managed only five tournaments this year due to a chronic back injury and has been reduced to playing exhibition doubles matches.
Agent Phil de Picciotto said Kournikova's return was "undetermined".
"I wouldn't put odds on it. She's playing some exhibitions later in the year and then she will see more from there," he told The Observer newspaper.
Kournikova has a chronic sprain of the lumbar spine, a condition which is inoperable.
"Playing too many days in a row, too many weeks in a row, is a problem," said De Picciotto. "Playing on occasions is not a problem.
"So the question is, as it would be for any top-level player, can she sustain the rigours of a year-long circuit that basically has no off season?"
De Picciotto also revealed that Kournikova had dispensed with the services of coach Harold Solomon, who was recruited to turn around the Russian's form last year.
Kournikova reached the semi-finals of Wimbledon in 1997 at the age of 16 and quickly established herself in the world's top 10.
However, a first WTA title continued to elude her and she soon faced criticism for her ability to attract millions in sponsorship despite apparently underachieving on court.
She suffered a stress fracture in her left foot in 2001 and failed to rediscover her form, despite the recruitment of Solomon.
The 22-year-old recently tried her hand at presenting at the US Open, but lasted only three days after admitting that she found interviewing her fellow players difficult.
Her one-time doubles partner Martina Hingis, also 22, was forced to quit the game earlier this year after suffering from severe ankle problems.
On Sunday, Russia's Maria Sharapova, who has attracted comparisons to Kournikova, lifted her first WTA trophy at the age of 16.