Triple Grand Slam winner Lindsay Davenport is pregnant with her second child and has pulled out of next month's Australian Open.
The 32-year-old former world number one will be off the tour indefinitely.
"Of course this unexpected but exciting surprise now means I will be putting tennis on hold for the foreseeable future," Davenport said in a statement on Wednesday.
The American returned to the tour last year after giving birth to her first child, Jagger, and has since won four titles.
Davenport has not played since the US Open, fuelling speculation she was ready to retire, but she entered the Australian Open last week.
The Californian has won 55 career titles and finished 1998, 2001, 2004, and 2005 as the world's top-ranked player. She is married to former All-American tennis player Jon Leach.
The Australian Open, the first Grand Slam tournament of 2009, begins on January 19.