Italian Lorenzo Musetti beat a "heartbroken" Stefanos Tsitsipas 1-6, 6-3, 6-4 on Friday to knock out the holder and reach the semi-finals of the Monte Carlo Masters.
Stefanos Tsitsipas beat Felix Auger-Aliassime 6-3, 6-3 in one hour and 28 minutes.
Carlos Alcaraz eased into the quarter-finals of the Rotterdam Open on Thursday with a comfortable straight-sets win over Italian qualifier Andrea Vavassori.
Two-time Grand Slam runner-up Stefanos Tsitsipas said "it sucks" after being on the end of the first big upset of the Australian Open on Monday
Stefanos Tsitsipas of Greece was stunned by 78th-ranked Alexander Shevchenko.
Alexander Zverev beat fierce rival Stefanos Tsitsipas in the quarter-finals of the Paris Masters on Friday, while Holger Rune edged Alex de Minaur to keep alive his hopes of reaching the ATP Tour Finals.
Both Daniil Medvedev and Stefanos Tsitsipas served sweet revenge at the Shanghai Masters on Friday, vanquishing old foes in straight sets as they progressed through to the third round.
The Greek, once ranked third in the world, has slipped out of the ATP top 10 in recent months to now stand at 12th.
The US Open brings down the curtain on the 2024 Grand Slam season with newly minted Olympic gold medallist Novak Djokovic aiming to add to his cache of major titles
Having clinched his fourth Grand Slam and back-to-back Wimbledon titles at the age of just 21, Spain's tennis star Carlos Alcaraz has the world at his feet.