She was also safe on her own serve, dropping just two games in the two-hour match while breaking Azarenka six times. She hadn't beaten Azarenka in their last seven matches, and had only won three of their previous 13.
"I said to myself one day I have to have one step forward and do the semifinal, and I'm so, so happy that I did it finally," Radwanska said of her first run to the semis of a major on hard courts. She reached the final at Wimbledon in 2012 and the semifinals last year.
"I knew she's very great player, very consistent," Radwanska said. "I just had to play my best tennis, even better and play aggressive and go for every shot I could."
Azarenka went down in a flurry of unforced errors, making 47 as she tried to claw her way back into the match.
She seemed to have momentum at the end of the second set, when she leveled after breaking Radwanska in the last game. But she didn't carry it through, pushing a forehand fractionally too wide on the first point and unsuccessfully challenging the out call.
It was a sign of things to come. She won only 14 points in the third set, and was broken three times.
She was booed late in the match, when she smashed a ball into the back of the court after another frustrating error. She screamed loudly after losing big points to the incredibly consistent Radwanska.
"She played well," Azarenka said, when asked about her obvious frustration on court. "I don't think I played my best tennis, but it didn't make me angry."
"My game wasn't there today as I wanted it to. But she definitely played really well."
