MELBOURNE, Australia - No fewer than 10 women have a shot at overtaking Simona Halep for the World No.1 ranking after the 2019 Australian Open, which kicks off on Monday, January 14th. 

Only two players held the No.1 ranking across the 2018 season. Halep started last season in the top spot, before Caroline Wozniacki wrestled it away by defeating Halep in a dramatic three-set battle to win her maiden Slam here at the Australian Open last January. Halep retook the No.1 ranking a month later and never looked back, becoming the first woman to finish No.1 in back-to-back seasons since Serena Williams.

Coming off an extended injury break, Halep will have to fend off 10 women who have a shot to overtake her in Melbourne, though all would need a deep run in the second week for a chance.

READ: WTA Insider Australian Open Draw Analysis

Before the first ball is hit on Monday, here are the women with a chance of unseating Halep. 

[NOTE: This post has been updated to reflect results from the Sydney International]

No.2 Angelique Kerber: Minimum Round Required - Semifinal
No.3 Caroline Wozniacki: Minimum Round Required - Title (eliminated if Halep wins 2R)
No.4 Naomi Osaka: Minimum Round Required - Quarterfinal
No.5 Sloane Stephens: Minimum Round Required - Quarterfinal
No.6 Elina Svitolina: Minimum Round Required - Final
No.7 Karolina Pliksova: Minimum Round Required - Final
No.8 Petra Kvitova: Minimum Round Required - Semifinal (Quarterfinal if she wins Sydney)
No.9 Kiki Bertens: Minimum Round Required - Final
No.10 Daria Kasatkina: Minimum Round Required - Title (eliminated if Halep plays 1R)
No.11 Aryna Sabalenka: Minimum Round Required - Title (eliminated if Halep wins 1R)

Halep is set to play Estonia's Kaia Kanepi in the first round on Tuesday, a rematch of their first-round encounter at the US Open last fall, which saw the big-hitting Estonian blast her way to the upset. Should Halep take the court to play the match, No.10 Daria Kasatkina will be out of the running to overtake her. If Halep wins her first round match, she will also eliminate Shenzhen Open champion Aryna Sabalenka from the No.1 sweepstakes. If she makes it to the third round, she will eliminate Wozniacki from contention.

READ: Simona Halep flying solo in Melbourne

US Open Champion Naomi Osaka and Sloane Stephens will need to make at least the quarterfinals for a chance at the No.1 ranking. Wimbledon champion Angelique Kerber, who is seeded No.2, must make at least the semifinals, as does Petra Kvitova, unless the Czech wins Sydney, in which case she must make at least the quarterfinals. WTA Finals champion Elina Svitolina, Brisbane International champion Karolina Pliskova, and Kiki Bertens must make at least the final to have a chance at No.1.

READ: WTA Insider Hard Court Power Rankings

Halep became the WTA World No.1 for the first time in her career on October 9, 2017, the first Romanian - and 25th WTA World No.1 in history - to achieve this historic milestone since the computer rankings were introduced in 1975. The 27-year-old remains only the 13th WTA player to achieve the year-end No.1 singles ranking after holding the top spot for 45 weeks in 2018, bringing her career total to 64. The two weeks of the 2019 Australian Open will be Halep’s 47th and 48th consecutive weeks atop the WTA Rankings.