The Polish second seed, who is chasing a maiden Melbourne title, wobbled before beating 31st Russian seed Anna Kalinskaya 6-1, 1-6, 6-1.

Swiatek faces qualifier Maddison Inglis next after Naomi Osaka pulled out of her third-round match against the Australian because of injury.

The former world number one Swiatek had no idea at the end of her match that Osaka had withdrawn.

"I don't know what my reaction should be," she said when told the news by the on-court interviewer.

"But I hope Naomi is well and it's exciting to be in the fourth round again."

Swiatek has won four French Opens, the US Open and Wimbledon, but a title at Melbourne Park has proved elusive.

Last year, she surged into the last four but failed to get past eventual winner Madison Keys.

Swiatek made a fast start, breaking Kalinskaya for an immediate 2-0 lead at Margaret Court Arena, where the roof was shut because of the hot weather.

It was 3-0 in 10 minutes as the 24-year-old threatened a quick conclusion.

The Pole wrapped up the first set up in 24 minutes, after which Kalinskaya needed a medical timeout and was seen by a physio. She had strapping on her lower back.

Next it was Swiatek's turn to suffer and go down by the same 6-1 scoreline. She then too had medical treatment.

They came out for the deciding set and it was all change again, Swiatek flipping a switch and smiling broadly at the end as she emerged victorious from a topsy-turvy encounter.

"I did not feel I was playing any worse in the second set, she just played in all the balls that went out in the first set," she said.

"I just kept going because the momentum can change for sure."

Swiatek arrived in Melbourne on the back of two singles defeats at the United Cup and was then pushed hard by Chinese qualifier Yuan Yue in round one.

She was more impressive in the second round, soaring past Marie Bouzkova of the Czech Republic for the loss of just five games.