Top seed Alexander Zverev crashed out of the BMW Open in the quarter-finals on Friday, 6-4, 6-4, against Chile's Cristian Garin.
Zverev struggled in windy and rainy conditions on a cool afternoon in Munich, losing in two hours after Garin broke him him once in each set and saved the two break points Zverev managed.
Olympic champion Zverev, who turns 27 on Saturday, pleaded in vain to officials to suspend the match because of the constant drizzle.
The 2017 and 2018 tournament winner had also lost to Garin in the same round in 2019, with Garin going on to lift the trophy.
"It is impossible for me to win in such weather. I tried everything. But in such conditions I have no weapons to win here," Zverev said, adding that Garin "deserved to win."
Garin next faces third seed American Taylor Fritz who edged Briton Jack Draper, 4-6, 6-3, 7-6 (7-1).
Danish title holder Holger Rune defeated Swiss player Marc-Andrea Hülser, 6-4, 7-6 (7-3).
Rune doesn't know his semi-final opponent yet because the final match between Jan-Lennard Struff and Felix Auger-Aliassime was abandoned due to darkness, with Germany's Struff up 7-5, 3-1 against his Canadian opponent.
