Ferrer will now face seventh seed Jo-Wilfried Tsonga for a place in the semifinals, after the Frenchman saw off Colombian qualifier Santiago Giraldo 6-3 6-4.
Seventh seed Jo-Wilfried Tsonga beat Colombian qualifier Santiago Giraldo 6-3 6-4 and will face Ferrer in the last eight, while fifth seed Robin Soderling went down 6-3 6-2 to Stanislas Wawrinka .
Tenth seed David Ferrer was taken to three sets in a 3-6 6-3 6-4 victory over Alexandr Dolgopolov but 13th seed Jurgen Melzer had little trouble in dispatching qualifier Santiago Giraldo 6-1 6-4.
But 19th seed Mardy Fish , runner-up to Roger Federer in Cincinnati , recovered from a mid-match wobble to overcome Jan Hajek 6-0 3-6 4-6 6-0 6-1 and 23rd seed Feliciano Lopez beat Santiago Giraldo in straight sets.
The eventual winner will play Thiemo De Bakker of the Netherlands in the next round, who was involved in another marathon battle with Santiago Giraldo, before coming through 16-14 in the final set - although that match lasted a mere four hours and six minutes.