The 32-year-old lost 6-7 (3-7), 1-6 to Italy's fourth-seeded Lorenzo Musetti. In the previous rounds, Struff had eliminated the French Ugo Humbert and the Serb Dusan Lajovic.

Struff's Davis Cup colleague Oscar Otte (Cologne) had already said goodbye in the round of 16 after a three-set defeat against Poland's Kamil Majchrzak.

However, only in singles: In doubles, Otte is at the side of Fabian Fallert after a 6:3, 7:5 over the top seeded Simone Bolelli/Fabio Fognini in the final.