Davydenko, the world number six, had beaten Lopez only once in five previous meetings and had to wait until the ninth game of the first set to break the Spaniard’s service.
The Russian took the first set and settled the match with an early double break in the second to leave Lopez still without a win in Rotterdam in his fifth attempt.
“It is always very tough against him on every surface,” Davydenko told reporters. “Today I had the feeling he automatically tried to play the tactical plan of our last three meetings.
“It gave me some problems in the beginning, but that also had to do with the extremely fast court.”
Davydenko, who defeated Roger Federer and Rafa Nadal in London last year and again in Doha this year, will face Cypriot Marcos Baghdatis who brushed aside James Blake 6-4 6-2 .
Swede Robin Soderling overcame Dutch qualifier Igor Sijsling 7-6 6-2 to reach the quarter-finals.
Soderling, eighth in the world rankings, trailed 4-0 then 6-4 in the first set tie-break before rallying to win the set.
“He didn’t surprise me today but it is always tough to play a qualifier who already had some matches in this tournament” Soderling said.
“I feel mentally and physically okay after some tough weeks and now I only need to start to play some better tennis”.
