The crafty Pole frustrated Azarenka with a scrambling, cat-and-mouse game early and completely dismantled the big Belarusian in the third set to close out the match in exactly two hours under bright sunshine at Rod Laver Arena.
"The best quarter-final for sure," Radwanska beamed in a courtside interview after snapping a seven-match losing streak to the world number two.
"I have played a couple of quarter-finals before and I said to myself one day I need to take one step forward and make the semi-final and final. I'm so, so happy that I did it finally.
"It was always hard. I have lost so many times against her before and I knew she was a very great player, very consistent so I just knew that I had to play my best tennis.
"Play aggressive and go for every shot that I could. That was what I was trying to do and it worked today."
Double defending champion Azarenka was a picture of torment, spraying unforced errors all over the centre court as she slumped to a 5-0 deficit in the first set.
She finally held serve in the sixth game and pummelled her legs with her fists, letting out an angst-filled shriek to try to shake herself out of her stupor.
She was powerless to prevent Radwanska from closing out the set, however, when she bamboozled the Belarusian with a deft drop-shot that was harmlessly pushed into the tramlines.
Azarenka rallied and pounced as Radwanska served to stay in the set at 6-5, blasting a string of fierce returns to bring up set points and levelled the match with a searing crosscourt winner.
The Belarusian dipped again, though, double-faulting to bring up a second break point in the opening game of the third set, and then losing serve when she floated a backhand long.
After Radwanska held for 2-0, Azarenka needlessly blasted a volley into the back of the court raising jeers from the crowd, and promptly lost the next four points to go a double-break down.
Tested on serve at 4-0, Radwanska raised huge roars from the terraces with a succession of exquisite points, scrambling down a series of would-be winners to hold, prompting Azarenka to crumble in the final game of the match.
"I just didn't have the focus on finishing the point... She really took advantage of that," Azarenka said.
"My game wasn't there as I wanted it ... She was aggressive, she was making everything."
5-Agnieszka Radwanska (Poland) beat 2-Victoria Azarenka (Belarus) 6-1 5-7 6-0
20-Dominika Cibulkova (Slovakia) beat 11-Simona Halep (Romania) 6-3 6-0
- Sports & Recreation
- Dominika Cibulkova
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