Melbourne - Former US Open champion Sloane Stephens became the highest seed to exit the women's draw on day one of the Australian Open on Monday.

The 2017 Grand Slam winner at Flushing Meadows and 24th seed in Melbourne lost in three sets to Zhang Shuai and is in the midst of a poor run of form.

The Chinese defeated the 26-year-old American 2-6, 7-5, 6-2 with Stephens having now lost all of her three matches in 2020.

Stephens similarly lost in three sets to Zhang in the first round in 2018.

Zhang, ranked 35th in the world, was treated to a rendition of 'happy birthday' by the crowd - she turns 31 on Tuesday.

"I tried to concentrate on every point. Thanks to all my team and the national team and coaches helping me in winter training - hard work!" said Zhang.

Collated results on day one of the Australian Open Grand Slam at Melbourne Park on Monday:

Men's singles

1st round

Matteo Berrettini (ITA x8) bt Andrew Harris (AUS) 6-3, 6-1, 6-3

Ricardas Berankis (LIT) bt Roberto Carballes (ESP) 6-4, 6-2, 6-2

Sam Querrey (USA) bt Borna Coric (CRO x25) 6-3, 6-4, 6-4

Guido Pella (ARG x22) bt John-Patrick Smith (AUS) 6-3, 7-5, 6-4

Gregoire Barrere (FRA) bt Mohamed Safwat (EGY) 6-7 (8/10), 7-6 (7/1), 6-4, 7-6 (7/5)

Marton Fucsovics (HUN) bt Denis Shapovalov (CAN x13) 6-3, 6-7 (7/9), 6-1, 7-6 (7/3)

Grigor Dimitrov (BUL x18) bt Juan Ignacio Londero (ARG) 4-6, 6-2, 6-0, 6-4

Daniel Evans (GBR x30) bt Mackenzie McDonald (USA) 3-6, 4-6, 6-1, 6-2, 6-3

Yoshihito Nishioka (JPN) bt Laslo Djere (SRB) 6-4, 3-6, 6-2, 7-6 (7/1)

Roger Federer (SUI x3) bt Steve Johnson (USA) 6-3, 6-2, 6-2

Stefanos Tsitsipas (GRE x6) bt Salvatore Caruso (ITA) 6-0, 6-2, 6-3

Philipp Kohlschreiber (GER) bt Marcos Giron (USA) 7-5, 6-1, 6-2

Novak Djokovic (SRB x2) bt Jan-Lennard Struff (GER) 7-6 (7/5), 6-2, 2-6, 6-1

Women's singles

1st round

Zhu Lin (CHN) bt Viktorija Golubic (SUI) 4-6, 6-1, 7-6 (10/5)

Julia Georges (GER) bt Viktoria Kuzmova (SVK) 6-1, 6-2

Petra Martic (CRO x13) bt Christina McHale (USA) 6-3, 6-0

Ekaterina Alexandrova (RUS x25) bt Jil Teichmann (SUI) 6-4, 4-6, 6-2

Barbora Krejcikova (CZE) bt Kaia Kanepi (EST) 7-6 (7/3), 2-6, 6-3

Paula Badosa (ESP) bt Johanna Larsson (SWE) 6-1, 6-0

Petra Kvitova (CZE x7) bt Katerina Siniakova (CZE) 6-1, 6-0

Naomi Osaka (JPN x3) bt Marie Bouzkova (CZE) 6-2, 6-4

Zheng Saisai (CHN) bt Anna Kalinskaya (RUS) 6-3, 6-2

Sorana Cirstea (ROU) bt Barbora Strycova (CZE x32) 6-2, 7-6 (7/5)

Ann Li (USA) bt Lizette Cabrera (AUS) 7-6 (7/4), 7-6 (12/10)

Sofia Kenin (USA x14) bt Martina Trevisan (ITA) 6-2, 6-4

Caroline Wozniacki (DEN) bt Kristie Ahn (USA) 6-1, 6-3

Tamara Zidansek (SLO) bt Han Na-lae (KOR) 6-3, 6-3

Serena Williams (USA x8) bt Anastasia Potapova (RUS) 6-0, 6-3

Ashleigh Barty (AUS x1) bt Lesya Tsurenko (UKR) 5-7, 6-1, 6-1

Coco Gauff (USA) bt Venus Williams (USA) 7-6 (7/5), 6-3

Caty McNally (USA) bt Samantha Stosur (AUS) 6-1, 6-4

Zhang Shuai (CHN) bt Sloane Stephens (USA x24) 2-6, 7-5, 6-2