Second seed Alexandr Dolgopolov set up a quarter-final showdown with former champion James Blake at the Citi Open in Washington.
Dolgopolov needed just 54 minutes to see off Ruben Ramirez Hidalgo 6-1 6-3, the Ukrainian taking advantage of three of his seven break points while not allowing his Spanish opponent a single break point in the match.
World number 25 Dolgopolov will now face 2002 winner Blake in the last eight, with the American defeating Swiss qualifier Marco Chiudinelli 6-2 6-4.
That victory improved Blake's record in 2012 to three wins in 11 matches having struggled with knee problems in recent years.
Also going through to the quarter-finals was fourth-seeded German Tommy Haas with a 6-4 7-5 triumph over Argentinian Leonardo Mayer.
Haas, who has now reached the Citi Open quarters five times in seven appearances, will next face compatriot Tobias Kamke, who also celebrated a straight-sets win in his second-round clash as he downed Marinko Matosevic of Australia 6-4 6-3.
