Self-proclaimed "obnoxious soccer mom" Victoria Azarenka was ordered to take off her Paris Saint-Germain shirt at the Australian Open on Thursday before bowing out of the Grand Slam with a straight-set defeat to Elena Rybakina in the semifinals.

The 33-year-old two-time champion has worn shirts showing support for French Ligue 1 champions PSG at the tournament as a gesture to her six-year-old son, who is also a big fan of the Paris club.

After an exchange of words with the chair umpire at Rod Laver Arena, Azarenka took off the PSG shirt before warming up in her regular kit against Rybakina.

"They told me to take it off twice because I had a different shirt," she told reporters after losing 7-6(4) 6-3 to Rybakina.

"I think it's the issue with the sponsorships. I guess the logos are too big ... I know that I'm not allowed to play in that. I knew those type of things.

"But I can still step on the court in what I want to step on the court. I do it for my own reasons.

"My son wore the white jersey today to his practice, and I tried to wear a white jersey to my match but couldn't. So that's okay."

That was the lesser of two disappointments for Azarenka on Thursday, as her bid for a third title in Melbourne ended with some regret at her missed chances against Rybakina.

The 2012 and 2013 champion gave up a break in the first set and converted only three out of eight break points in the match.

Up 0-40 on Rybakina's serve at 5-5 in the first set, Azarenka could capitalise and suffered a loss in momentum as her error count grew and her opponent's confidence rose.

"I'm proud of myself how I fought and I tried, but just was not -- tennis-wise I felt like [I] just wasn't there, especially in the important moments when I kept creating those opportunities," Azarenka said.

"Not a great feeling right now to digest.

"But give me a couple of hours and I can have probably a better outlook on this month in Australia. I look forward to, throughout the year, what I can do."

Rybakina will face World No. 5 Aryna Sabalenka, who hasn't lost a set in the tournament, on Saturday.