Lleyton Hewitt won the battle of the Australians, defeating Chris Guccione to advance to the quarter-finals of the Regions Morgan Keegan Championships in Memphis on Friday.
Hewitt set up a clash with Belgian Christophe Rochus with a 6-2 7-6 (7-4) victory over his compatriot.
Rochus upset American seventh seed Mardy Fish 6-2 6-4.
Second seed Juan Martin Del Potro ousted Latvian star Ernests Gulbis 6-3 6-4, while fifth seed Radek Stepanek accounted for Austrian Stefan Koubek 6-2 6-4.
Other players to advance were Russian Igor Kunitsyn and Israeli Dudi Sela.
Top seed Andy Roddick downed fellow American Robbie Ginepri 6-2 6-3, but Marcos Baghdatis was crushed 6-1 6-2 by American No.8 seed Sam Querrey.
In the women's draw, Caroline Wozniacki advanced to the semi-finals with a 2-6 6-3 6-3 victory over Dutch qualifier Michaella Krajicek.
Top seed Wozniacki needed two hours, nine minutes to overcome a slow start against Krajicek, who committed six double-faults in the third set.
It was a surprisingly difficult match for Wozniacki as she reached her first WTA semi-final of the season. The Dane won the first three titles of her career last year and climbed to a career-high ranking of 12th.
The 18-year-old Wozniacki's next opponent will be fourth-seeded Brit Anne Keothavong, who posted a 6-2 1-6 6-2 victory over fifth seed Marina Erakovic of New Zealand.
Sixth-seeded German Sabine Lisicki continued her push towards a first title with a 6-3 6-4 win over No.3 seed Lucie Safarova of the Czech Republic.
The world No.61 faces a much sterner test in the semi-finals when she will face 15th-ranked Victoria Azarenka.
The second seed from Belarus advanced with a 6-4 6-2 win over eighth seed Pauline Parmentier of France.
Results from the Regions Morgan Keegan Championship, Memphis
Men's second round
2-Juan Martin Del Potro (Argentina) def. Ernests Gulbis (Latvia) 6-3 6-4
5-Radek Stepanek (Czech Republic) def. Stefan Koubek (Austria) 6-2 6-4
Christophe Rochus (Belgium) def. 7-Mardy Fish (USA) 6-2 6-4
Lleyton Hewitt (Australia) def. Chris Guccione (Australia) 6-2 7-6 (7-4)
Igor Kunitsyn (Russia) def. Philipp Petzschner (Germany) 3-6 6-4 6-4
Dudi Sela (Israel) def. Florent Serra (France) 7-6 (7-4) 7-6 (7-4)
Women's quarter-finals
1-Caroline Wozniacki (Denmark) def. Michaella Krajicek (Netherlands) 2-6 6-3 6-3
2-Victoria Azarenka (Belarus) def. Pauline Parmentier (France) 6-4 6-2
6-Sabine Lisicki (Germany) def. 3-Lucie Safarova (Czech Republic) 6-3 6-4
4-Anna Keothavong (Great Britain) def. 5-Marina Erakovic (New Zealand) 6-2 1-6 6-2