Dechy was one game away from losing to local favorite Nicole Pratt before pulling out a 2-6, 7-5, 6-3 victory. The 29-year-old Frenchwoman next faces eighth-seeded Barbara Schett of Austria in the quarterfinals.
"I've never won against her so I think I will have nice day tomorrow to change it," Dechy said.
Bovina held off fellow Russian Nadia Petrova, 5-7, 6-3, 6-3. The 19-year-old from Moscow will next take on Italian Tathiana Garbin, a 6-0, 6-4 winner over South African qualifier.
Sixth seed Meghann Shaughnessy of the United States defeated Lina Krasnoroutskaya of Russia, 6-3, 7-6 (8-6), despite twisting her ankle in the final moments of her victory.
Shaughnessy, who played with a heavily taped strained calf muscle, will undergo treatment on her ankle and expects to be ready to play top-seeded Patty Schnyder of Switzerland in the quarterfinals.