Dementieva, the runner-up in this tourney a year ago, ousted Anastasia Pavlyuchenkova 6-4, 6-4 on the hard courts at Stade Coubertin. Pennetta defeated Alisa Kleybanova 7-6 (7-4), 6-1.
It was the first action of the week for both players after they received first-round byes.
They were joined in the quarterfinals by Tathiana Garbin, who surprised eight-seeded Elena Vesnina 6-4, 2-6, 6-2 and earned a meeting with Pennetta on Friday.
The first round concluded with Petra Martic downing Yanina Wickmayer 6-4, 3-6, 7-5 and Aravane Rezai eliminating Evgeniya Rodina 6-4, 6-4.
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