MELBOURNE, Australia - Serena Williams continues her chase for history while the defenders and contenders aim to solidify their spots at the top of the sport at the 2019 Australian Open. As the players make their final preparations for the first Slam of the year, WTA Insider digs into the numbers to illustrate what's at stake in Melbourne. 

8: Different Slam champions in the last eight Slams (Serena Williams, Jelena Ostapenko, Garbiñe Muguruza, Sloane Stephens, Caroline Wozniacki, Simona Halep, Angelique Kerber, Naomi Osaka).

5: Active Slam champions who have won the Australian Open (Serena Williams, Maria Sharapova, Victoria Azarenka, Angelique Kerber, and Caroline Wozniacki).

18: Women in the Australian Open draw who have made at least one major final.

9: Number of Top 16 seeds who were not Top 16 seeds at the Australian Open last year. 

11: Women who have a chance of leaving Melbourne Park with the No.1 ranking.

1978: The last time an Australian woman won the Australian Open singles title (Chris O'Neil).

3: Players using their special ranking to earn direct entry into the main draw: Timea Bacsinszky, Laura Siegemund, and Bethanie Mattek-Sands.

1: Main draw withdrawal (CoCo Vandeweghe, left ankle injury).

3: Players seeded at a Slam for the first time: No.21 Wang Qiang, No.29 Donna Vekic, and No.31 Petra Martic. 

64: Ranking spots climbed by Naomi Osaka in the last 12 months. The No.4 seed was ranked No.68 twelve months ago.

67: Ranking spots climbed by Aryna Sabalenka in the last 12 months. Now ranked No.11 and on the brink of her Top 10 debut, the Belarusian was ranked No.78 twelve months ago. 

10: Points No.5 Sloane Stephens, No.8 Petra Kvitova, and No.11 Aryna Sabalenka are each defending in Melbourne. 

READ: WTA Insider Hard Court Power Rankings

2000: Points World No.3 Caroline Wozniacki is defending in Melbourne, where she won her maiden major last year.

0: Points No.16 Serena Williams is defending until March.

23: Major singles titles won by Serena Williams, the most in the Open Era. 

24: Major singles titles won by Margaret Court, the all-time record. 

7: Australian Open singles titles won by Serena Williams, the most of any woman in the Open Era. Margaret Court, Evonne Goolagong Cawley, Stefanie Graf, and Monica Seles each won four.

81: Main draw appearances at a Slam for Venus Williams, the most in the Open Era.

9: Women who have won the US Open and Australian Open back-to-back in the Open Era. Reigning US Open champion Naomi Osaka is bidding to become the 10th and 1st since Kim Clijsters won the 2010 US Open and 2011 Australian Open.

6: Times a top seed lost in the first round of a Slam in the Open Era. Simona Halep became the 6th last fall when she lost to Kaia Kanepi in the first round of the US Open. Halep plays Kanepi in the first round on Tuesday.

25: Times a player aged 30 or over has won a Slam singles title in the Open Era. The last woman to do so was Angelique Kerber at Wimbledon last summer.