Denis Shapovalov was surprisingly beaten in straight sets by 21-year-old Ugo Humbert at the Auckland Open on Friday.
A day after first and third seeds Fabio Fognini and Karen Khachanov were knocked out, second seed Shapovalov was beaten 7-5 6-4.
Humbert, who broke serve in the final game of each set, described the win as "one of the biggest of my career" as he set up a semi-final against John Isner.
The American was taken to two tie-breaks by Kyle Edmund but prevailed 7-6 (7-5) 7-6 (7-5), his 25 aces getting him over the line as he seeks a third title in Auckland.
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Benoit Paire reached his first semi-final at the event, coming from a set down to beat John Millman 3-6 6-1 6-4.
The fifth seed will face Hubert Hurkacz, who spurned six second-set match points in a mammoth tie-break before eventually seeing off Feliciano Lopez 6-4 6-7 (11-13) 6-4.
At the Adelaide International, home favourite Alex Bolt was soundly beaten by Felix Auger-Aliassime, the Canadian needing just 55 minutes to win 6-3 6-0.
He will meet Andrey Rublev in the last four after the Russian battled past Dan Evans 6-4 3-6 6-3 in just over two hours.
Spanish hopes were extinguished in the quarter-finals, where Tommy Paul surprised Albert Ramos-Vinolas to win 6-3 6-4 and Lloyd Harris beat fourth seed Pablo Carreno Busta 6-3 6-3.
