Australian Jordan Thompson upset US top seed John Isner 7-6 (7/2), 6-7 (3/7), 6-3 to reach the ATP New York Open quarter-finals.
Thompson, who will face Italy's Andreas Seppi on Friday for a berth in the semi-finals, avenged a loss to Isner in last year's New York quarter-finals.
The world number 63 took his first victory in four meetings with the big-serving American.
"Pretty stoked with that," Thompson said.
"It was a tough match. Didn't get much of a look at his serve. I got one break and managed to hold on somehow."
The 25-year-old from Sydney surged ahead 5-0 in the first tie-breaker, then fell behind 4-1 in dropping the second only to take the lone break of the match in the final set.
"I just told myself to keep going and I would get a look," Thompson said.
"And luckily I pulled it off."
Defending champion Reilly Opelka beat Japan's Yoshihito Nishioka 6-4, 6-4, sending the US third seed into a quarter-final against Taiwan's Jason Jung, who upset British seventh seed Cameron Norrie 6-4, 6-4.
British eighth seed Kyle Edmund defeated Germany's Dominik Koepfer 6-2, 6-4 to book a last-eight date with South Korean Kwon Soon-woo.
The other quarter-final sends French fourth seed Ugo Humbert against Serbian sixth seed Miomir Kecmanovic.
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