Two-time champion John Isner made it safely into the quarter-finals of the ATP hardcourt tournament at Winston-Salem on Wednesday, where compatriot Sam Querrey toppled second-seeded Kevin Anderson in straight sets.
Querrey, seeking a third straight semi-final appearance in the US Open tune-up, downed Anderson 7-6 (7/4), 6-4 to stretch his career record over the South African to 7-4.
"I played great out there. That was the best I've played all summer," said the 56th-ranked Querrey. "I was aggressive the whole time and returned well. I thought everything went pretty well."
Querrey next faces Spanish fifth seed Guillermo Garcia-Lopez, who saved two match points in a 6-7 (4/7), 6-3, 7-6 (8/6) win over American Donald Young.
Isner, the top seed, defeated 13th seed Mikhail Kukushkin of Kazakhstan 6-1, 7-6 (7/3). Isner, a North Carolina native who won this title in 2011 and 2012, didn't face a break point in the 68-minute match, firing 17 aces.
In Thursday's quarter-finals, Isner will face seventh-seeded Czech Lukas Rosol, who beat Spain's Pablo Andujar 1-6, 6-2, 6-2.
Taiwan's Lu Yen-Hsun also booked a quarter-final berth, cruising past Spain's Marcel Granollers 6-1, 6-2.
He'll face Andreas Seppi of Italy, who beat France's Nicolas Mahut 6-4, 7-6 (9/7).
Belgian qualifier David Goffin extended his unbeaten run to 25 matches, beating Finland's Jarkko Nieminen 6-4, 4-6, 6-4 to set up a clash with Jerzy Janowicz. Poland's Janowicz dispatched France's Edouard Roger-Vasselin 4-6, 6-3, 6-4.
"It was a great fight and I'm really happy the way I played at the end to win this match," said Goffin, who hasn't lost a match since his first-round exit at Wimbledon.
"Of course, after 25 matches you have a lot of confidence, you don't think you're going to lose, but I play every match like it's the first one in the tournament, like it's the first one of the season and I give everything."