Novak Djokovic beaten 4-6, 7-5, 6-4 by 21-year-old Italian Lorenzo Musetti. The world No.1 has won the Monegasque tournament only twice, in 2013 and 2015.
The other quarter of the table will pit Diego Schwartzman (9th) against Daniil Medvedev (11th) Jannik Sinner saved a match ball but lost to Hubert Hurkacz (13th) in the last 16.