PARIS -- Anna Kournikova's tennis career could be in jeopardy after her agent said Tuesday that a long-standing back injury might ultimately force her to retire from the game.

In the latest issue of the French sports daily L'Equipe, agent Phil De Picciotto said that the 22-year-old Kournikova may be forced to dramatically reduce her playing schedule -- if she is even able to play again.

Kournikova has had a miserable run of results over the past couple of seasons and did not play in the French Open or Wimbledon because of her injury. She has played only five tournaments this year and recently withdrew from the entire summer hard-court season, including the U.S. Open.

"Considering the state of her back, Anna is unable to [play] in tournaments regularly," De Picciotto told L'Equipe. "The past six months have proved that she has a real desire to play, but even if she feels better, she is not fit enough to play as much as she used to."

The pin-up girl of tennis, Kournikova has never won a singles title on the WTA Tour; her riches predominantly have been earned through sponsorship deals. She tried to resurrect her career in May by playing on the Challenger circuit, but had to withdraw due to her back ailment.

The Russian's best performance in seven years as a professional came when she reached the semifinals of Wimbledon in 1997. She reached a career-high eighth in the world rankings in December 2000.