Andy Roddick reached the quarter-finals of the ATP Regions Morgan Keegan Championships in Memphis for the ninth successive year.
The defending champion clinched a straight-sets victory over Chinese Taipei's Yen-Hsun Lu.
The American triumphed 7-6 (7/2) 6-4 in his second-round match to set up a last-eight meeting with compatriot Sam Querrey.
Querrey, the eighth seed, encountered few problems in seeing off Argentina's Leonardo Mayer 6-4 6-0.
Fifth-seeded Czech Tomas Berdych was given a stern test by American Michael Russell but eventually prevailed 3-6 6-3 6-2 and will face Latvia's Ernests Gulbis in the last eight.
Croatia's Ivo Karlovic also progressed with a 6-4 6-4 win over Belgian Xavier Malisse while Lukas Lacko won through after Frenchman Jeremy Chardy retired with a stomach illness with the Slovakian 7-6 (7/4) 2-1 up in their clash.
Karlovic will play American John Isner in the quarter-finals while Lacko will take on Philipp Petzschner of Germany.
In the WTA Cellular South Cup, top-seeded Russian Maria Sharapova enjoyed a straight-sets passage to the semi-finals but second seed Melanie Oudin and third seed Kaia Kanepi crashed out.
American Oudin went down 6-1 6-3 to Swedish qualifier Sofia Arvidsson and fifth-seeded Czech Petra Kvitova battled back to defeat Estonia's Kanepi 1-6 6-3 7-6 (7/0).
Sharapova saw off eighth seed Elena Baltacha 6-2 7-5, but there will be British interest in the last eight after Anne Keothavong overcame Croatia's Karolina Sprem 6-4 6-3 in their quarter-final.
Sharapova will take on Kvitova in the semi-finals, while Keothavong will face Arvidsson.
