Georgia's Nikoloz Basilashvili upset Croatian top seed Ivo Karlovic 7-6 (7/2), 6-3, to reach the quarter-finals of the ATP Memphis Open.
A week shy of his 25th birthday, the world number 67 on Thursday won all 37 of his first-serve points and took only 69 minutes to dispatch hard-serving 37-year-old Karlovic, ranked 20th.
Basilashvili, seeking his first ATP crown, advanced to the last eight at the indoor hardcourt event, where he will meet Australian qualifier Matthew Ebden, who downed US teen Taylor Fritz. 6-4, 4-6, 6-3 after one hours and 42 minutes.
Kazakhstan's Mikhail Kukushkin dispatched Barbados qualifier Darian King 6-3, 6-0 in 70 minutes to book a quarter-final spot against US fourth seed Steve Johnson, who rallied to oust compatriot Tim Smyczek 3-6, 6-4, 6-2.
Kukushkin connected on 65 percent of his first serves and won 82 percent of his first-serve points while King managed to take only 36 percent of his first-serve points.
Friday's other quarter-finals send US second seed John Isner against compatriot Donald Young and American Ryan Harrison against Bosnian Damir Dzumhur.