Jennifer Capriati is recovering from an "accidental overdose" of prescribed medication, according to a spokeswoman for the three-time Grand Slam winner.
The 34-year-old former world number one was rushed to hospital in South Florida early on Sunday morning by paramedics.
But Lacey Wickline told The Associated Press that the American is now "stable" and expected to make "a full recovery".
Capriati won the 1992 Olympics, the 2001 Australian and French Opens and the 2002 Australian Open title.
She turned professional at the age of 14 in 1990 and reached the semi-finals of Wimbledon a year later, after defeating then defending champion Martina Navratilova.
But her career was derailed by off-court problems, including a shoplifting incident in 1993 and an arrest for possession of marijuana the following year.
She did not play at all in 1995 but subsequently returned to the highest echelons of the game and picked up her three Grand Slam titles.
Her playing career was finally ended in 2005 after she underwent surgery for a persistent shoulder problem.
Source : BBC News