World number one Aryna Sabalenka said she was "emotionally all over the place" as she squeezed past Anastasia Potapova to reach the Australian Open fourth round.
The Belarusian, a heavy favourite for a title she has already won twice, was cruising at a set and 4-0 up.
However, the 27-year-old was left feeling "disconnected from my body" as 55th-ranked Potapova fought back, with Sabalenka forced to fend off four set points before clinching a 7-6 (7-4) 7-6 (9-7) victory.
Afterwards, a reflective Sabalenka admitted it was a match she would have gone on to lose earlier in her career.