WINSTON-SALEM, North Carolina, Aug 21 AFP – 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 in North Carolina.

He 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.