The 82nd-ranked Golubev lost the only previous meeting against No. 6 Davydenko, who was coming back after breaking his left wrist.
Third-seeded Juergen Melzer of Austria, the French Open semifinalist, advanced to the last eight by beating Jeremy Chardy of France 7-5, 7-6 (4) for his 15th win in the last 20 matches.
Sixth-seeded Juan Carlos Ferrero of Spain beat Jarkko Nieminen of Finland 6-2, 3-6, 6-4 to reach the quarterfinals of the clay-court tournament for the first time in nine years.
Ferrero reached the final in 2001 but hadn't been past the third round in any of his other five attempts.
Seventh-seeded Thomaz Bellucci of Brazil defeated No. 10 Philipp Kohlschreiber of Germany 7-5, 6-4, while Denis Istomin of Uzbekistan beat wild card Julian Reister of Germany 3-6, 6-3, 7-6 (3).
Florian Mayer of Germany made the last eight by dispatching Maximo Gonzalez of Argentina 7-6 (1), 6-0.
In other early matches, Andreas Seppi edged Fabio Fognini 6-4, 6-4 in an all-Italian encounter and another Italian, Potito Starace, advanced by rallying to beat Spanish qualifier Pere Riba 4-6, 6-4, 6-4.
In the quarterfinals, Golubev plays Istomin, Mayer meets Ferrero, Starace faces Melzer and Bellucci goes against Seppi.