Anna Kournikova has been advised today to take three months rest from tennis by her German doctor who is treating the Russian for a stress fracture in her foot to heel.
Hubert Hoerterer was quoted by Germany's Sport1 website saying Kournikova would not be able to play without pain until the injury was fully healed.
On Monday she pulled out of next week's U.S. Open because of the injury - the second time in three years she has missed the event.
"It will take at least another three months before Anna can play in a tournament again," Hoerterer said of Kournikova, who had been given the 19th seed in the U.S. Open.
Kournikova, who has never won a professional tournament but is nevertheless the biggest earning women on the tour thanks to endorsements, had also pulled out of Wimbledon and the French Open because of the injury to her left foot.
"Only when the stress fracture is fully healed can Anna play tennis again later without any pain," he added. "Anything else is nonsense because the injury could be exacerbated again."
Hoerterer, who has also treated former German soccer star Matthias Sammer and German skier Katja Seizinger, said he had warned Kournikova against a hurried return to the WTA Tour in June.
But she entered a tournament in San Diego, where she lost her opening round match to Nicole Pratt of Australia.
The pain worsened and she was forced to drop plans to play in tournaments in Los Angeles and Toronto.
"Anna was also diagnosed with a stress fracture quite some time ago," Hoerterer said. "That injury was also not properly cured and, more importantly, the cause of the injury was not dealt with."