Flavia Pennetta, who played the last tournament of her career - the WTA Finals - as the World No.7, isn't the first player to go out at the top of her game. Here are the 15 players who retired while in the Top 10, including six players who retired while in the Top 5 - and someone who retired at No.1:
Margaret Court (AUS)
Court, who won 24 Grand Slam titles in her career, which still stands as the record for most Grand Slam titles all-time, was ranked No.5 in the world when she retired from professional tennis in 1977.
Olga Morozova (RUS)
Morozova, a two-time Grand Slam finalist, retired in 1977 when she was still No.10 in the world.
Greer Stevens (RSA)
South Africa's first Top 10 player, Stevens - pictured center - was No.10 when she retired in 1980.
Chris Evert (USA)
Evert was a fixture at the top of the WTA Rankings, finishing Top 3 every year from 1975 to 1988. She was ranked No.4 in the world when she played the last tournament of her career, the 1989 US Open.
Manuela Maleeva-Fragnière (SUI)
Pictured right, Bulgarian-born Swiss Maleeva-Fragnière retired in 1994 at No.9 in the world.
Martina Navratilova (USA)
Navratilova retired from singles competition in 1994 when she was No.6. She would keep playing doubles, though, until 2006 - she also played a handful of singles events between 2002 and 2005.
Kimiko Date-Krumm (JPN)
Date-Krumm, then Date, retired at the end of 1996 when she was No.8 in the world. Almost a dozen years later, in the fall of 2008, the ageless Japanese returned to the tour and is still going strong.
Steffi Graf (GER)
After a phenomenal Channel Slam - winning the French Open, the finals of Wimbledon - Graf, the Open Era record-holder for most Grand Slam titles with 22, announced her retirement. She was No.3.
Kim Clijsters (BEL)
Clijsters retired from the tour in 2007 as a one-time Grand Slam champion and World No.4. She came out of retirement as a mom in 2009 and went on to win three more majors before re-retiring in 2012.
Justine Henin (BEL)
A seven-time Grand Slam champion and dominant World No.1, Henin suddenly retired a few weeks before the 2008 French Open while still ranked No.1. She came back in 2010 before re-retiring in 2011.
Elena Dementieva (RUS)
Two-time Grand Slam finalist Dementieva called it a career at the end of 2010 at No.9 in the world.
Li Na (CHN)
Two-time Grand Slam champion and former World No.2 Li retired in the fall of 2014 ranked No.5.
Flavia Pennetta (ITA)
Last but not least, talk about going out on a high. Pennetta, who had never been ranked higher than No.10 in the world beforehand, broke back into the Top 10 at No.8 after winning her fairytale first Grand Slam title at the US Open this year, and subsequently announced she'd be retiring at the end of the season. She made it as high as No.6 and played her last tournament, the WTA Finals, as the No.7.