Young Australian Jordan Thompson has lost in three sets in the quarter-finals of the New York Open.
Thompson started well on Friday, winning the opening set against Andreas Seppi, but the Italian rallied to win 6-7 (2-7) 6-4 6-1.
In the last four, Seppi will face Jason Jung, the giantkilling American-born professional who represents Taiwan.
The 30-year-old Jung upset third-seeded American Reilly Opelka 5-7 6-4 6-4. Jung has beaten both of the tournament's past champions en route to his first career semi-final.
Jung won only two matches on tour last year - both in this tournament - and qualified this week for the main draw. He ousted 2018 champion Kevin Anderson in the first round.
Opelka, who won his lone career title last year on Long Island, had been the highest-seeded player remaining.
That mantle goes to No.6 Miomir Kecmanovic, who has come back to beat fourth-seeded Frenchman Ugo Humbert 3-6 6-2 6-4.
Kecmanovic will play British No.8 seed Kyle Edmund, who edged Soonwoo Kwon 3-6 6-2 7-6 (7-5).