Defending champion Flavio Cobolli was eliminated from the Hamburg Open in the first round.
The 24-year-old Italian lost to Peruvian qualifier Ignacio Buse 2-6, 5-7 on Tuesday.
Just a few days before the start of the French Open, Cobolli was unable to build on his recent strong performances on clay. About a month ago, he had reached the final at the tournament in Munich.
The second Grand Slam tournament of the season begins on Sunday in Paris.