Mercurial Benoit Paire tasted his first win over a top-ten player since 2017 when he defeated fifth seed Denis Shapovalov in the second round of the Western and Southern Open in Cincinnati.
Rain earlier in the day forced a 11 pm local time start and Paire was quick off the blocks as he won the first set 6-3.
Shapovalov broke his opponent's serve in the opening game to take an early lead and the Canadian would then go on to level the tie as he won the set 6-4.
In the decider, the Canadian seemed to be in control when he broke to lead 2-0.
Paire broke back to make it 2-2 when Shapovalov netted a volley.
The Frenchman's casual brilliance came to the fore with some of his strokeplay and he completed the upset when Shapovalov netted a backhand return.
Paire won 6-3, 4-6, 7-5 and will now play the winner of Jannik Sinner vs John Isner second round match.
Former top-ten ranked Gael Monfils of France beat Dusan Lajovic of Serbia in straight sets to book his place in the second round of the Western and Southern Open on Tuesday.
Monfils won 7-6 (0), 6-2 and keeps his hundred per cent record against the Serbian in head-to-head meetings.
In another match, American Frances Tiafor fought hard to overcome Frenchman Ugo Humbert to advance.
Tiafoe won 7-5, 7-6 (9) and will now play Argentina's Diego Schwartzman while Monfils will clash against Australian Alex de Minaur.
Meanwhile, former world number one Victoria Azarenka sealed her spot in the second round after beating Ludmilla Samsonova in two straight sets.
The Belarussian triumphed 6-2, 6-3 over the Russian in only one hour and nine minutes, dominating her first serve and breaking Samsonova five times throughout the match.
