American Isner sent down 17 aces in a 6-1 7-6 (7-3) win over Kazakh Mikhail Kukushkin in their third-round clash at the ATP 250 tournament.
Isner, the top seed and champion in 2011 and 2012, was largely untroubled thanks to his big serve.
Kukushkin, the 13th seed, only managed to win nine return points on the hard courts in North Carolina as Isner set up a quarter-final meeting with Lukas Rosol.
Czech seventh seed Rosol recovered from a slow start to beat Spanish 10th seed Pablo Andujar 1-6 6-2 6-2.
On the other side of the draw, South African second seed and wildcard Anderson went down 7-6 (7-4) 6-4 to American Sam Querrey.
The duo combined for 19 aces, but Querrey broke once in the second set and only lost four points on his serve.
Querrey will face fifth seed Guillermo Garcia-Lopez after the Spaniard battled past American left-hander Donald Young 6-7 (4-7) 6-3 7-6 (8-6).
Young, the 11th seed, led 4-1 and 6-4 in the third-set tie-break before squandering two match points in the loss.
Belgian qualifier David Goffin will face Pole Jerzy Janowicz in a last-eight clash.
Goffin made it 25 straight wins with a 6-4 4-6 6-4 victory over Finnish 15th seed Jarkko Nieminen, while Janowicz edged French 12th seed Edouard Roger-Vasselin 4-6 6-3 6-4.
Italian 14th seed Andreas Seppi beat Frenchman Nicolas Mahut 6-4 7-6 (9-7) and will face Chinese Taipei's Lu Yen-Hsun, who thrashed Spanish eighth seed Marcel Granollers 6-1 6-2.