Two-time Grand Slam winner Garbine Muguruza won after a tough struggle. She defeated Australia's Ajla Tomljanovic 6-3, 3-6, 6-3. Croatia's Donna Vekic and world number-2 Czech Republic's Karolina Pliskova also reached the third round. In the men's singles, World No. 4 Russia's Daniil Medvedev also won. The fourth day game of the Australian Open started with a delay of about 4 hours due to rain, strong winds, and fog.

Garbine won Wimbledon in 2017 and the French Open in 2016. In the women's singles, Donna defeated France's Alize Cornet 6-4, 6-2. She reached the third round of the tournament for the first time. At the same time, Carolina defeated Laura Siegemund of Germany 6-3, 6-3. World number-7 Switzerland's Belinda Bencic defeated Latvia's Jelena Ostapenko 7-5, 7-5.

Daniil Medvedev, who entered the tournament for the fourth time in the men's singles, defeated Spain's Pedro Martinez 7-5, 6-1, 6-3. This is the second time he has reached the third round of the tournament. The last time he was out in the fourth round. At the same time, Ernests Gulbis of Latvia, ranked 256, defeated world number-55 Aljaz Bedene of Slovenia 7-5, 6-3, 6-2.