Davydenko will face fourth-seeded Juan Martin del Potro of Argentina for a place in the quarterfinals.
In other first-round matches, France's Nicolas Mahut and Albano Olivetti and Russia's Igor Kunitsyn advanced in straight sets. David Goffin of Belgium led 6-2, 1-0 against Adrian Mannarino when the Frenchman retired.
Olivetti beat Matthias Bachinger of Germany 6-4, 6-3. Karol Beck served 11 aces in beating French wild card Paul-Henri Mathieu 7-6 (2), 2-6, 6-3. The Slovak will next play big-serving Ivan Ljubicic, the seventh-seeded Croat.