From start to finish it was tight, but in all the important moments it was Pironkova who rose up, and the Bulgarian qualifier eventually edged the No.3-seeded Italian in just under two hours, 76(2) 63.
"I definitely felt good out there," Pironkova said afterwards. "This result actually makes me very happy considering the results I had last year. This actually shows that I did a good job in the off-season.
"Last year was very disappointing if you exclude Wimbledon and a couple of quarterfinals. What happened? I really don't know. The off-season last year I was working so hard - I never worked that hard in my life. But it just didn't work for me. I started to get anxious. I don't think that helped me a lot.
"This off-season I decided to change things a little, taking it easier and working more on my fitness. Also my tennis, but not as much as I used to. I also did work on my mentality. I think I'm just taking things easier now. I feel more relaxed and I enjoy playing. I guess that's what makes the results come."
Pironkova is now into her second-biggest WTA semifinal, her biggest being Wimbledon in 2010. Also, her win over the World No.7 was her ninth Top 10 win, after the 2006 Australian Open (No.10 Venus Williams), 2008 Rome (No.3 Ana Ivanovic), 2009 Moscow (No.7 Vera Zvonareva), 2010 Warsaw (No.5 Elena Dementieva), 2010 Wimbledon (No.2 Venus Williams), 2011 Wimbledon (No.3 Vera Zvonareva), 2012 Paris [Indoors] (No.9 Li Na) and finally 2012 Eastbourne (No.3 Agnieszka Radwanska).
The Bulgarian will have to bring her A-game again in the semifinals - awaiting her there is the No.6-ranked, No.2-seeded Petra Kvitova, who beat fellow Czech lefty Lucie Safarova in straights, 76(4) 62.
"Lucie's a good friend of mine - we know each other very well on and off of the court because we practiced a lot together in Prostejov and on the Fed Cup team," Kvitova said afterwards. "So I know exactly how she can play, and I knew what she would try, and I just tried to do my best out there.
"My serve was great today. It helped me a lot. The first set was really good tennis from both of us, and then when I broke her in the second set I felt more up, so I just tried to keep my serve from there."
Kvitova was asked why so many Czech players are lefty. "Maybe something in the water!" she said.
Kvitova has beaten Pironkova in all three previous meetings, though the last two have gone to three sets - including their quarterfinal battle at Wimbledon in 2011, when Kvitova eventually won the title.