Melbourne - Six-time champion Serena Williams was handed a tough draw on Friday at the Australian Open, while defending champion Angelique Kerber has a slightly easier route towards another final.
The American powerhouse, bidding for a 23rd Grand Slam crown at the tournament starting in Melbourne on Monday, faces dangerous former world No 7 Belinda Bencic of Switzerland in the opening round.
Second seed Williams, who lost the top ranking to Kerber last year, could then encounter in-form Briton Johanna Konta in the fourth round and Slovak sixth seed Dominika Cibulkova in the quarters.
She could potentially then meet her US Open conqueror Karolina Pliskova in the semi-final of the bottom half of the draw.
Williams' drop to world No 2 was triggered by her shock defeat to Pliskova at Flushing Meadows last year, which also denied her the chance to better Steffi Graf's 22 Grand Slam victories.
Pliskova is seeded to meet two-time Melbourne Park semi-finalist Agnieszka Radwanska in the quarter-finals.
World number one Kerber is seeded for a last eight clash with Spanish seventh seed and French Open champion Garbine Muguruza in the top half of the draw.
Kerber, who beat Williams to win the first of her two Grand Slams last year in Melbourne, starts with a first-round clash against Ukraine's Lesia Tsurenko.
Winning the Australian Open in 2016 sparked a memorable season for the German, who followed it up by claiming the US Open.
She has two potential testing opponents early in her campaign with a re-match against Russian teen Daria Kasatkina, who upset her in this week's lead-up Sydney International.
The 19-year-old Russian, ranked 26, shocked Kerber 7-6 (7/5), 6-2 in a second-round match played in sweltering conditions.
Former Wimbledon finalist Eugenie Bouchard, who rediscovered some form at the Sydney International in reaching the semi-finals, is another potentially in Kerber's way.
Romania's world number four Simona Halep opens with a match against American Shelby Rogers and could face a quarter-final against either Ukraine 11th seed Elina Svitolina or experienced Russian eighth seed Svetlana Kuznetsova.
Draw made on Friday for the Australian Open women's singles in Melbourne (x denotes seeding):
Angelique Kerber (GER x1) v Lesia Tsurenko (UKR)
Qualifier v Carina Witthoeft (GER)
Kristyna Pliskova (CZE) v Viktorija Golubic (SUI)
Yaroslava Shvedova (KAZ) v Irina-Camelia Begu (ROU x27)
Daria Kasatkina (RUS x23) v Peng Shuai (CHN)
Louisa Chirico (USA) v Eugenie Bouchard (CAN)
Pauline Parmentier (FRA) v Misaki Doi (JPN)
Coco Vandeweghe (USA) v Roberta Vinci (ITA x15)
Carla Suárez Navarro (ESP x10) v Jana Cepelova (SVK)
Irina Khromacheva (RUS) v Sorana Cirstea (ROU)
Alison Riske (USA) v Madison Brengle (USA)
Qualifier v Zhang Shuai (CHN x20)
Anastasija Sevastova (LAT x32) v Nao Hibino (JPN)
Kristina Kucova (SVK) v Christina McHale (USA)
Samantha Crawford (USA) v Lauren Davis (USA)
Marina Erakovic (NZL) v Garbine Muguruza (ESP x7)
Simona Halep (ROU x4) v Shelby Rogers (USA)
Ashleigh Barty (AUS) v Annika Beck (GER)
Qualifier v Destanee Aiava (AUS)
Patricia Maria Tig (ROU) v Monica Puig (PUR x29)
Kiki Bertens (NED x19) v Varvara Lepchenko (USA)
Duan Ying-ying (CHN) v Qualifier
Qualifier v Kurumi Nara (JPN)
Kateryna Kozlova (UKR) v Venus Williams (USA x13)
Elina Svitolina (UKR x11) v Galina Voskoboeva (KAZ)
Francesca Schiavone (ITA) v Qualifier
Vania King (USA) v Qualifier
Evgeniya Rodina (RUS) v Anastasia Pavlyuchenkova (RUS x24)
Laura Siegemund (GER x26) v Jelena Jankovic (SRB)
Katerina Siniakova (CZE) v Julia Goerges (GER)
Anna Tatishvili (USA) v Jaimee Fourlis (AUS)
Mariana Duque-Marino (COL) v Svetlana Kuznetsova (RUS x8)
Karolina Pliskova (CZE x5) v Sara Sorribes Tormo (ESP)
Qualifier v Monica Niculescu (ROU)
Qualifier v Jelena Ostapenko (LAT)
Lara Arruabarrena (ESP) v Yulia Putintseva (KAZ x31)
Daria Gavrilova (AUS x22) v Naomi Broady (GBR)
Ana Konjuh (CRO) v Kristina Mladenovic (FRA)
Danka Kovinic (MNE) v Zheng Saisai (CHN)
Camila Giorgi (ITA) v Timea Bacsinszky (SUI x12)
Elena Vesnina (RUS x14) v Qualifier
Mandy Minella (LUX) v Magda Linette (POL)
Qualifier v Johanna Larsson (SWE)
Heather Watson (GBR) v Samantha Stosur (AUS x18)
Alize Cornet (FRA x28) v Myrtille Georges (FRA)
Maria Sakkari (GRE) v Anett Kontaveit (EST)
Mirjana Lucic-Baroni (CRO) v Wang Qiang (CHN)
Tsvetana Pironkova (BUL) v Agnieszka Radwanska (POL x3)
Dominika Cibulkova (SVK x6) v Denisa Allertova (CZE)
Karin Knapp (ITA) v Hsieh Su-Wei (TPE)
Sara Errani (ITA) v Risa Ozaki (JPN)
Ekaterina Alexandrova (RUS) v Ekaterina Makarova (RUS x30)
Caroline Wozniacki (DEN x17) v Arina Rodionova (AUS)
Donna Vekic (CRO) v Lizette Cabrera (AUS)
Luksika Kumkhum (THA) v Naomi Osaka (JPN)
Kirsten Flipkens (BEL) v Johanna Konta (GBR x9)
Barbora Strycova (CZE x16) v Qualifier
Kayla Day (USA) v Andrea Petkovic (GER)
Cagla Buyukakcay (TUR) v Oceane Dodin (FRA)
Kateryna Bondarenko (UKR) v Caroline Garcia (FRA x21)
Timea Babos (HUN x25) v Nicole Gibbs (USA)
Irina Falconi (USA) v Han Xinyun (CHN)
Yanina Wickmayer (BEL) v Lucie Safarova (CZE)
Belinda Bencic (SUI) v Serena Williams (USA x2)