SINGAPORE - Martina Hingis has hung up her racquets and retired after reaching the semifinals of the BNP Paribas WTA Finals Singapore presented by SC Global.

Hingis officially made her announcement on social media on Friday, after advancing to the last four with partner Chan Yung-Jan at the WTA Finals.

"Now that the cat is out of the bag, here we are for the third, and final time," Hingis wrote on Facebook, referring to previous two retirements. "Looking back now, it's hard to believe that almost exactly 23 years ago I made my professional debut. The years that followed have been some of the most rewarding years of my life, both personally and professionally, but I believe the time has come for me to retire, which I will be doing after my last match here in Singapore.

"This isn't goodbye. As history shows, I haven't been able to stay away from tennis for long in the past, and I am looking forward to seeing what new opportunities lie ahead of me. I believe the best is yet to come and will continue to share my experiences with you!"

Read Hingis' full message here.

Here's a look at the numbers behind the 23-year career of one of the game's most prodigious talents.

2: Age Hingis first learned how to play tennis under the tutelage of her mother, Melanie Molitor.

12: Age Hingis won the junior French Open title in 1993. She won three junior Slam titles in total.

Hingis competing at Wimbledon in 1993. (Getty)

1994: Year Hingis made her WTA debut at the age of 14 at the Zurich Open.

15: Age Hingis won her first Slam title in 1996, winning the doubles at Wimbledon with Helena Sukova to become the youngest major titlist in history.

16: Age Hingis won her first WTA singles title in Filderstadt in 1996.

38: Match win-streak in singles to start the 1997 season.

16: The age at which Hingis won the 1997 Australian Open singles title, becoming the youngest Australian Open titlist in history.

1997: The year Hingis first ascended to No.1, becoming the youngest WTA No.1 in history at age 16.

7: Grand Slam singles finals Hingis made in her career (Roland Garros: 1997, 1999; Australian Open: 2000, 2001, 2002; US Open: 1998, 1999)

6: Players to hold both the singles and doubles No.1 rankings simultaneously.

29: Weeks Hingis held the singles and doubles No.1 rankings simultaneously. Only Martina Navratilova held both for longer (103 weeks).

2003: Year Hingis retired at the age of 22 due to injuries.

2005: Year Hingis returned to the tour after her first retirement.

2007: Year Hingis retired for a second time at the age of 27.

2013: Year Hingis was inducted into the International Tennis Hall of Fame in her first year of eligibility.

Martina Hingis received her Hall of Fame ring from Tennis Hall of Fame CEO Todd Martin during the WTA Finals in 2015. (Getty)

2013: Year Hingis returned to the tour to focus on doubles. She played her first tournament in five years with Daniela Hantuchova in Carlsbad.

209: Total weeks spent at No.1 in singles.

3: Times Hingis finished the year as the year-end No.1 in singles (1997, 1999, 2000).

548: Career singles match wins.

43: Singles titles won, tied for 12th in WTA history.

64: Career doubles titles, 12th best in WTA history.

13: Slam doubles titles.

19: Years between her first Australian Open doubles title in 1997 and her fifth and final Australian Open title in 2016.

5: Grand Slam singles titles, including three at the Australian Open.

17: Years between her first Miami Open doubles title in 1998 and her last in 2015.

1: Calendar Slam in doubles in 1998.

40: Different doubles partners with which Hingis won her 64 career doubles titles.

31: Tournaments played with Sania Mirza, the most with any single partner.

14: Doubles titles won with Mirza, the most successful partnership of her career. Their last win came at 2016 Rome.

18: Tournaments played with Anna Kournikova, the second most with any single partner.

11: Doubles titles won with Kournikova, the second most successful partnerhsip of her career, with the last coming at 2002 Australian Open

16: Doubles tournaments played with her current partner, Chan Yung-Jan, including this week as the top seeds at the WTA Finals. They have won nine doubles titles as a team.

9: Different mixed doubles partners.

7: Mixed doubles titles at the Slams. She won her first mixed doubles title in 2006 and her last this year at the US Open, a span of 21 years.

2016: Year Hingis made the French Open mixed doubles final, thus completing her set of having made all 12 major finals in each of the three disciplines (singles, doubles, mixed).