Australian qualifier Matthew Ebden completed the quarter-final draw at the Memphis Open by beating last year's runner-up Taylor Fritz in the day's final match.
The world No.490 saw off his American opponent 6-4 4-6 6-3 to set up a last-eight clash with Nikoloz Basilashvili, who accounted for top-seeded Ivo Karlovic 7-6 (7-2) 6-3.
Basilashvili, ranked 67th in the world, never dropped his serve and allowed the 20th-ranked Karlovic just one break-point opportunity.
In other second-round action, fourth-seeded Steve Johnson beat fellow American Tim Smyczek 3-6 6-4, 6-2. Johnson lost the first set and fell behind 3-1 in the second set before rallying.
Johnson will face Mikhail Kukushkin, a 6-3 6-0 winner over Barbadian Darian King, who conquered Australian No.5 seed Bernard Tomic earlier in the week.
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The other quarter-final matchups have No. 2 seed John Isner facing fellow American Donald Young and Ryan Harrison taking on Damir Dzumhur.
Karlovic's loss leaves Isner and Johnson as the only seeds left in the field.
