Unseeded Pole Magda Linette has continued her dream run at the Australian Open, upsetting former world number one Karolína Plíšková to claim a semifinal berth.

Linette, 30, made the crucial break in the 11th game of the second set and held her nerve to serve out the match, winning 6-3 ,7-5 in one hour and 27 minutes.

She will play Aryna Sabalenka in the semifinals after the fifth-seeded Belarusian defeated unseeded Croatian Donna Vekić 6-3, 6-2.

In her previous 29 appearances at the majors, Linette had never advanced further than the third round.

"It's so emotional. I can't really believe it," Linette said in her on-court interview after beating 30th-seeded Plíšková.

"Dreams come true. We keep going though.

"I don't want to get too excited because we're still in the tournament but I'm super grateful and happy."

Late-blooming Linette, ranked 45 in the world, admitted she had become much better at managing her emotions on the court.

"All through my life, I've been taking mistakes and losses very personally, so I had to disconnect those two things," she said.

"It was really difficult because I felt a lot of times that the misses, the mistakes, were defining me.

"My coaches and I did a really great job and I'm really thankful to them."

All five of Linette's scalps at Melbourne Park this year have been ranked inside the top 50 in the world.

The loss means Plíšková's long wait for a maiden grand-slam tournament title continues.

The 30-year-old Czech has lost both of her major finals — at the 2016 US Open to Angelique Kerber and at Wimbledon two years ago to Ash Barty.

Sabalenka had only won one of her previous six matches against Vekić, but was able to turn that around with her straight-sets triumph.

She is now unbeaten in nine matches this year after winning the Adelaide International 1 title.

"Vekić is a great player and it is tough to play against her,” Sabalenka said.

"I was kind of expecting this game from her. I was able to stay in the game, no matter what."

AAP