Brazilian youngster João Fonseca was defeated by Germany's Yannick Hanfmann at the grass-court Halle Open on Tuesday, with newly crowned French Open champion Alexander Zverev also in appearance.
The 19-year-old Fonseca, who beat Novak Djokovic in a five-set thriller at Roland Garros last month, fell in straight sets 6-2, 6-2 to world number 59 Hanfmann, celebrating his 100th victory on the ATP Tour.
Hanfmann converted his first match point against the French Open quarter-finalist after just 66 minutes.
"My first win here on Centre Court – that means a great deal to me," said the Karlsruhe native after his opening victory in Halle, which serves as a warm-up to Wimbledon.
Hanfmann is also playing doubles at the tournament in western Germany, officially known as the Terra Wortmann Open, alongside compatriot Jan-Lennard Struff, with the pair having taken the Stuttgart title last week.
Top seed Zverev faces Vit Kopriva from the Czech Republic in his first appearance since winning his long-awaited first major title in Paris over Italy's Flavio Cobolli on June 7.
Cobolli was knocked out in Halle on Monday by Frances Tiafoe, while Felix Auger-Aliassime advanced in three sets against Nuno Borges.
Elsewhere on Tuesday, Kazakh seventh seed Alexander Bublik suffered a surprise loss to Italian qualifier Mattia Bellucci, 7-6 (8-6) 6-1.
Australian maverick Nick Kyrgios had to withdraw from the tournament in Halle at short notice after sustaining an injury to his right knee during training ahead of his first-round match against Ben Shelton.
