Second seed Nikolay Davydenko remained on course for his fifth ATP Tour title after a straight-sets win over Juan Monaco.
The 28-year-old Russian took one hour and 42 minutes to see off the world number 30, coming through 6-3 7-5 at the Valencia Open.
It was not all plain sailing for the world number seven though, who committed four double-faults in the second set. He now takes on Guillermo Garcia-Lopez in the quarter-finals.
In the first match of the day on! the Agora court, Russia's Mikhail Youzhny overcame Uruguayan Pablo Cuevas in three sets.
The 27-year-old world number 23 won a topsy-turvy match 6-2 2-6 6-1 in one hour and 34 minutes in the pair's first ATP Tour encounter.
Youzhny will now take on Frenchman Gilles Simon, seeded fifth, in the last eight.
Top seed Andy Murray faces Argentina's Leonardo Mayer tonight.
