Halep plays in the first round of Estonia's Kaia Kanepi on Tuesday, a rematch of the first-round encounter at the US Open last fall, which saw the powerful Estonian go furious. Should Halep take over the game, defending champion Wozniacki and No. 10 Daria Kasatkina will be out of the race to overtake. If Halep wins her match in the first round, she will also beat Shenzhen No. 1 winner Aryna Sabalenka.
READ: Simona Halep flies solo in Melbourne
US Open champion Naomi Osaka and Sloane Stephens have to reach at least the quarter-finals to claim a first-place chance. Wimbledon champion Angelique Kerber, who was seeded # 2, has to make at least the semifinal, as well as WTA Finals champion Elina Svitolina and Petra Kvitova. The Brisbane World Champion, Karolina Pliskova and Kiki Bertens, must at least make the final to have a chance at # 1