Seeded pair Benoit Paire and Cristian Garin were dumped out of the German Tennis Championships on Monday, along with two-time former champion Leonardo Mayer.
A day of upsets saw Paire go down to countryman Jeremy Chardy, while Garin went out to Andrey Rublev.
Fifth seed Paire scraped through the opening set but ultimately came up short, losing 6-7 (4-7) 7-5 6-3.
Mayer's defeat was perhaps the most shocking reverse, though, as he lost to 18-year-old wildcard Rudolf Molleker in straight sets.
Home hopeful Molleker came through a first-set tie-break 10-8 and then secured the only break of the match to see off the 2014 and 2017 winner. Mayer had also reached the final last year.
He was the only German player to win on Monday, however, as Martin Klizan - himself a former champion - eased past Daniel Altmaier.
Philipp Kohlschreiber was easily dispatched by Marton Fucsovics.
At the Swiss Open Gstaad, 2014 winner Pablo Andujar came through three sets against Dennis Novak, while Roberto Carballes Baena also advanced.
Corentin Moutet exited at the hands of Cedrik-Marcel Stebe, but Stefano Travaglia, who defeated Fabio Fognini at last week's Croatia Open Umag, progressed.