Karolina Pliskova smashed two racquets and argued with the umpire in her 7-5 7-5 third-round loss to Karolina Muchova at the Australian Open.

She then walked into the players' tunnel and broke another racquet before being reported by an official.

World number one Ashleigh Barty advanced to the fourth round with victory over Ekaterina Alexandrova.

Home favourite Barty came out on top in a staccato match, beating the Russian 6-2 6-4.

Barty lost the first two games of the first set before winning six in a row to close out the opener.

She again went a break down in the second, with Alexandrova finding her range after treatment on her abdomen, but Barty upped her level to win the final four games.

She will play Shelby Rogers for a spot in the quarter-finals after the American beat Estonian 21st seed Anett Kontaveit 6-4 6-3.

'I can do what I want' - Pliskova unimpressed

Pliskova was left unimpressed when she was given a second penalty for breaking the racquet.

"It's off court, I'm allowed to do what I want," Pliskova argued after being docked a point for a second violation.

Chair umpire Alison Hughes told Pliskova that she was not allowed to destroy any equipment during a match.

The incident seemed to fire up Pliskova's game as the former world number one then raced into a 5-0 lead in the second set before losing seven games in a row to see her bid for a maiden Grand Slam title come to an end.

International Tennis Federation (ITF) rules state players are not allowed to "violently or with anger hit, kick or throw a racquet or other equipment within the precincts of the tournament site".

Pliskova hit 40 unforced errors to 23 winners and has not reached the quarter-finals of a Grand Slam since the 2019 Australian Open.

"I don't feel safe with anything that I was really doing on the court," she said.

"Of course, I played quite amazing to 5-0, but then it's quite tough to hold this level for a longer time."

Czech Muchova will play 18th seed Elise Mertens of Belgium, who breezed past Swiss 11th seed Belinda Bencic 6-2 6-1, for a place in the quarter-finals.

Fifth seed Elina Svitolina advanced to the second week with a 6-4 6-0 win over Yulia Putintseva of Kazakhstan.

Ukrainian Svitolina will play Jessica Pegula after the American stopped France's Kristina Mladenovic 6-2 6-1.

Donna Vekic saved match point and overturned a 3-0 third-set deficit to beat dangerous Estonian Kaia Kanepi.

Kanepi had ended Sofia Kenin's title defence in the second round and Croatia's Vekic had to dig deep to win 5-7 7-6 (7-2) 6-4.

She will play American Jennifer Brady, who continued her good form with a 6-1 6-3 win over Slovenian qualifier Kaja Juvan.

There are no fans at the Australian Open as Melbourne enters a five-day lockdown.