Yastremska is ranked 93 in the world, and her 7-6, 6-4 win over 18th seed Azarenka is not her first shock result in Melbourne having beaten Wimbledon champion Marketa Vondrousova (24) in the first round.
It's almost two years since the war in Ukraine began, and in that time Yastremska has failed, until now, to make it past the opening round of a Grand Slam tournament.
"I was putting a lot of pressure on myself in different ways," Yastremska said.
"In the way that it's the war and I have to show better results, you know, for Ukraine, and I wasn't playing just for myself in the beginning.
"But now I decided that from this year no more pressure, no more high expectations for myself. Just be the way you are, and we will see how it's going to go."
For now, it couldn't be going any better, but while she is learning to deal with the pressures, reminders of what is happening in her native Ukraine are never far away, even if others may have already moved on.
Yastremska recently revealed that before her first round defeat in the Brisbane International earlier this month, a rocket hit her grandmother's house.
"It's tough emotionally to play, but the worst thing is you feel like you are already accepting this, what is happening," Yastremska said.
"And people are starting to forget about what is going on. Just in general, it's tough to play, but after two years you get to manage already how to deal with all the emotions and with everything that is going on inside."
Yastremska was asked if there had been extra pressure playing against Azarenka, from Belarus, given her country's involvement as a staging post for Russian troops.
"If I'm going to start talking about it, I think you're not going to like my answers so I'm just going to say I want to skip this question," she said.
"Because I think, if you're asking this question, I'm sure you know how is it for us, for Ukrainians to play against Russians and Belarusian."
In a tournament which has seen top seeds such as Iga Swiatek (22) and Elena Rybakina (24) already exit the competition, Ukraine has two women in the quarter-finals, with Marta Kostyuk (21) joining her compatriot.
"Yeah, I'm proud of Marta as well and I'm proud of us, of Ukrainians, and we are showing good results," Yastremska said.
"She had tough matches. She also had to deal with playing with Russians."
Yastremska now faces Czech Linda Noskova (19) for a place in the semi-final while Kostyuk is up against American fourth seed Coco Gauff (19).
