The 31-year-old Italian could do nothing wrong in the first set, moving Kerber around the court and belting winners from both sides to take it 6-1 in 24 minutes.
Kerber, who lost in the Sydney International final to qualifier Tsvetana Pironkova, took a short break between sets and somehow managed to stay in the match and break the 29th-seed three times to send it to a decider.
Pennetta was broken twice in the third set but rediscovered her rhythm and accuracy to break Kerber three times to advance to her first singles quarter-final at Melbourne Park against either Chinese fourth seed Li Na or Russia's Ekaterina Makarova.
Image: Flavia Pennetta
Photograph: Quinn Rooney/Getty Images
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