Top-ranked Novak Djokovic and Simona Halep, as expected, were given the No. 1 seedings on Thursday when the Australian Open announced its singles seedings list.
Defending champion Roger Federer is seeded No. 3 after Rafael Nadal, while women's defending singles champion Caroline Wozniacki, who beat Halep in last year's final at Melbourne Park, is No. 3 behind second-seeded and 2016 champion Angelique Kerber.
Serena Williams, who won the Australian Open in 2017 while pregnant with daughter Alexis Olympia, returns as the 16th-seeded player after missing last year's tournament.
Fifth-ranked Juan Martin del Potro will miss the Australian Open while he recovers from a fractured right kneecap.
Men's Singles
1. Novak Djokovic, Serbia
2. Rafael Nadal, Spain
3. Roger Federer, Switzerland
4. Alexander Zverev, Germany
5. Kevin Anderson, South Africa
6. Marin Cilic, Croatia
7. Dominic Thiem, Austria
8. Kei Nishikori, Japan
9. John Isner, United States
10. Karen Khachanov, Russia
11. Borna Coric, Croatia
12. Fabio Fognini, Italy
13. Kyle Edmund, Britain
14. Stefanos Tsitsipas, Greece
15. Daniil Medvedev, Russia
16. Milos Raonic, Canada
17. Marco Cecchinato, Italy
18. Diego Schwartzman, Argentina
19. Nikoloz Basilashvili, Georgia
20. GrigorDimitrov, Bulgaria
21. David Goffin, Belgium
22. Roberto Bautista Agut, Spain
23. Pablo Carreno Busta, Spain
24. HyeonChung, South Korea
25. Denis Shapovalov, Canada
26. Fernando Verdasco, Spain
27. Alex de Minaur, Australia
28. Lucas Pouille, France
29. Gilles Simon, France
30. Gael Monfils, France
31. Steve Johnson, United States
32. Philipp Kohlschreiber, Germany
Women's Singles
1. Simona Halep, Romania
2. Angelique Kerber, Germany
3. Caroline Wozniacki, Denmark
4. Naomi Osaka, Japan
5. Sloane Stephens, United States
6. Elina Svitolina, Ukraine
7. Karolina Pliskova, Czech Republic
8. Petra Kvitova, Czech Republic
9. Kiki Bertens, Netherlands
10. Daria Kasatkina, Russia
11. Aryna Sabalenka, Belarus
12. Elise Mertens, Belgium
13. Anastasija Sevastova, Latvia
14. Julia Goerges, Germany
15. Ashleigh Barty, Australia
16. Serena Williams, United States
17. Madison Keys, United States
18. Garbine Muguruza, Spain
19. Caroline Garcia, France
20. Anett Kontaveit, Estonia
21. Wang Qiang, China
22. JelanaOstapenko, Latvia
23. Carla Suárez Navarro, Spain
24. Lesia Tsurenko, Ukraine
25. Mihaela Buzarnescu, Romania
26. Dominika Cibulkova, Slovakia
27. Camila Giorgi, Italy
28. Hsieh Su-wei, Taiwan
29. Donna Vekic, Croatia
30. Maria Sharapova, Russia
31. Petra Martic, Croatia
32. Barbora Strycova, Czech Republic