Kuznetsova may be ranked No.75, but that's because she missed the entire second half of 2012 with a knee injury, and it said nothing of her abilities - a two-time Grand Slam champion, two-time finalist, former World No.2 - and there was something else, the fact she has six wins over World No.1s, the fourth-most among active players after Serena Williams, Venus Williams and Maria Sharapova.
This was a clear dark horse, not just for the upset, but maybe even for the whole thing - and in the early goings things looked dicey for Azarenka, as Kuznetsova built a 4-1 lead in the opening set.
But Azarenka wouldn't have any of it, battling back to win that tight 77-minute opening set then cruising in the 30-minute second set, moving through to the semifinals with a runaway 75 61 victory.
"I feel like at the beginning it was a little bit like play around, a lot of back and forth," Azarenka said. "We were both producing good tennis, but I felt like she was a little bit on top of me on the important moments. I didn't really take advantage, and she did. That's why she had the lead at the start.
"But then I turned it around and took control in my hands. That's what I felt was a turning point."
"These matches against such top players, you have to play very consistently," Kuznetsova said after the match. "That's what has killed me since my break, my consistency - and I didn't serve well, either. So those were the two key points. That's what I didn't do well during the match. That's why I lost."
Azarenka talked about riding the wave of ups and downs during a match. "You cannot expect to have your best tennis on every single point, on every single game," the World No.1 commented. "But it's important to know that when you need it, it's there and you can rely on that. That's what gives you confidence. That's what keeps you fighting all the time, that you just have to try and try and try."
Azarenka was also asked whether she was excited being even deeper into the business end of the tournament now. "It would be silly to say I'm not excited, I'm not nervous," she said. "I think the person who is never nervous is a really scary person. I mean, that person is a robot, really.
"Everybody has emotions. It's just a matter of how well you can control them for you to feel good before you go on the court, or when you're on the court. It's just a matter of how well you prepare yourself mentally, physically, to be in the state of mind that you want to be out there on the tennis court."
For Kuznetsova, the quarterfinals of a Grand Slam in just her third tournament back from a six-month lay-off was quite the performance - and the World No.75 could go as high as No.50 after this.
"After a long break, not such a long preparation, I did quite well I think," Kuznetsova said. "I played a lot of matches in Sydney, and played quite good matches here too, and that's all I needed. I feel like I have game. I can play. But I need to improve my fitness, my consistency, my serve - there's a lot.
"And then we'll see where I can be at."