US second seed John Isner blasted 26 aces Wednesday in rallying to defeat Japan's Yoshihito Nishioka 4-6, 6-3, 6-4 and advance to the ATP Memphis Open quarter-finals.
Isner took one hour and 49 minutes to book a Friday last-eight date with compatriot Donald Young, who advanced with a 7-6 (7/3), 6-3 triumph over American teen Reilly Opelka in the indoor hardcourt event.
Bosnian Damir Dzumhur upset Belgian seventh seed Steve Darcis 7-6 (7/2), 6-4 in another second-round match. He will face American Ryan Harrison - who eliminated US third seed Sam Querrey 6-3, 6-1 - in another Friday quarter-final.
In first-round matchups, Georgia's Nikoloz Basilashvili downed Australia's Jordan Thompson 6-3, 6-0, and Kazakhstan's Mikhail Kukushkin ousted German lucky loser Benjamin Becker 6-3, 6-4.
Kukushkin will next face Barbados qualifier Darian King while Basilashvili meets Croatian top seed Ivo Karlovic on Thursday.