Top seed Andy Roddick had to dig deep in a tough encounter with Rajeev Ram before booking his place in the quarter-finals of the Atlanta Tennis Championships.
The world number nine, back in action for the first time since Wimbledon, became the fifth American to reach the last eight of the hard-court tournament by posting 6-1 6-7 (1/7) 6-3 triumph.
Roddick joins John Isner, Mardy Fish, Taylor Dent and Michael Russell as the US contingent in the next round.
Next up for the 2003 US Open champion is a meeting with seventh seed Xavier Malisse, who advanced with a 6-3 6-3 win over Ukraine's Illya Marchenko.
Roddick defeated Malisse in the Atlanta final in 2001, the last time the ATP Tour visited the city prior to this year, and enjoys an 8-0 career record against the Belgian.
Donald Young failed to make it six Americans in the last eight as he went down to a 7-5 6-3 defeat at the hands of South African Kevin Anderson, while third seed Lleyton Hewitt was a surprise casualty as he lost 6-4 6-2 to Slovakia's Lukas Lacko.