Melbourne - Spain's Garbine Muguruza said she narrowly avoided turning into a zombie before reaching the Australian Open last 16 Saturday after playing her previous match in the middle of the night.
The two-time Grand Slam winner, seeded 18, defeated Timea Bacsinszky of Switzerland 7-6 (7/5), 6-2 to make the fourth round at Melbourne Park.
The 25-year-old's previous match against Briton Johanna Konta set a record for the latest start in the tournament's history after it began in the early hours of Friday morning.
The clash, which Konta condemned as dangerous and unhealthy, began at 12:30 am and finished after a draining three sets at 3:12 am, the latest end to a women's match at the Grand Slam.
Muguruza said it made preparation difficult for her match against Bacsinszky.
"I tried to fall asleep quickly and stay active a bit, not like a zombie," she said. "But I felt good on the court."
Muguruza, a quarter-finalist in Melbourne two years ago, will face either Czech seventh seed Karolina Pliskova or 27th seed Camila Giorgi of Italy in the next round.
The Spaniard is seeking to recapture the form that propelled her to the world number one ranking and delivered a French Open title in 2016 and Wimbledon a year later.
Collated results from Day 6 of the Australian Open on Saturday:
Daniil Medvedev (RUS x15) bt David Goffin (BEL x21) 6-2, 7-6 (7/3), 6-3
Kei Nishikori (JPN x8) bt Joao Sousa (POR) 7-6 (8/6), 6-1, 6-2
Pablo Carreno-Busta (ESP x23) bt Fabio Fognini (ITA x12) 6-2, 6-4, 2-6, 6-4
Milos Raonic (CAN x16) bt Pierre-Hugues Herbert (FRA) 6-4, 6-4, 7-6 (8/6)
Novak Djokovic (SRB x1) bt Denis Shapovalov (CAN x25) 6-3, 6-4, 4-6, 6-0
Alexander Zverev (GER x4) bt Alex Bolt (AUS) 6-3, 6-3, 6-2
Borna Coric (CRO x11) bt Filip Krajinovic (SRB) 2-6, 6-3, 6-4, 6-3
Lucas Pouille (FRA x28) bt Alexei Popyrin (AUS) 7-6 (7/3), 6-3, 6-7 (10/12), 4-6, 6-3
Naomi Osaka (JPN x4) bt Hsieh Su-wei (TPE x28) 5-7, 6-4, 6-1
Elina Svitolina (UKR x6) bt Shuai Zhang (CHN) 4-6, 6-4, 7-5
Anastasija Sevastova (LAT x13) bt Wang Qiang (CHN x21) 6-3, 6-3
Serena Williams (USA x16) bt Dayana Yastremska (UKR) 6-2, 6-1
Madison Keys (USA x17) bt Elise Mertens (BEL x12) 6-3, 6-2
Simona Halep (ROU x1) bt Venus Williams (USA) 6-2, 6-3
Garbine Muguruza (ESP x18) bt Timea Bacsinszky (SUI) 7-6 (7/5), 6-2
Karolina Pliskova (CZE x7) bt Camila Giorgi (ITA x27) 6-4, 3-6, 6-2