The match had several momentum swings - first Petkovic went up a set and a break at 64 21, then Azarenka battled back to take the second set and go up 2-0 in the third, then the two found themselves locked at 4-all in the third. But one last push from Petkovic put her over the finish line, as she snuck out the last two games at love - a love break, then a love hold - to end it after two hours and 22 minutes.
"I'm very happy with my performance," Petkovic said. "I was happy with my movement and my serve for the most part, and I managed to get a lot of balls back very deep and very strong. Parts of the match were a really, really good level - some parts I lost a bit of energy, but overall I'm very happy."
Petkovic always seems to lift her game in Beijing - she reached the biggest final of her career, in fact the only Premier-level final of her career, right here in 2011 (falling to Agnieszka Radwanska).
"I always play really well here," Petkovic said. "I lost in the first round here last year but I was playing Jelena Jankovic, who was playing really well that day. I really like the courts - I really like the atmosphere and center court. I don't know, it's just a tournament that goes with my play somehow!"
Next up for Petkovic is another former China Open champion, in fact the only two-time champion in the tournament's 10-year history, Svetlana Kuznetsova. Kuznetsova beat Hsieh Su-Wei earlier on, 61 61.
"I've played her a lot of times, three or four times maybe, and I've had some bad losses but some wins also," Petkovic said. "I just have to focus on my performance and hopefully play another good match."
Meanwhile, Azarenka wasn't happy with her performance at all - she talked about it in her presser.
"It was an awful match and a very bad performance from me, so there's not much to say about it," the World No.2 commented. "It happens once, twice a year to every player, and it happened to me today."
"If I did it all again, I probably should have taken a longer break and prepared myself better. I don't feel like I was ready to play - to be 100%, the preparation wasn't enough, I cannot deny that. It's my mistake for not paying enough attention after the US Open how I managed my time and managed my health.
"But you cannot put yourself down too much. In the end the important thing is how you come out of it. I'm going to go back, reevaluate and practice more. I just needed more preparation, and that's what I'm going to get now before the last tournament. I'll just look at the positives. I have three weeks now."
Petkovic scored her second win over a Top 2 player (also No.1 Caroline Wozniacki at 2011 Miami).