Germany's Alexander Zverev had his hopes of a third triumph at the Madrid Masters dashed by Argentinian Francisco Cerundolo in the last 16 on Tuesday.
The Olympic champion, who lost 3-6, 4-6, had won the clay-court tournament in the Spanish capital in 2018 and 2021 and had already reached the quarter-finals five times.
Zverev didn't play with enough variety to put the tactically disciplined Cerundolo under any pressure in their first direct duel.
A break for 5-3 (first set) and 2-1 (second set) were enough for the Argentinian to make it through to the last eight after an hour and a half. The 25-year-old will face Taylor Fritz from the US.
Zverev has lost three of his seven matches in this year's clay-court season so far. There is not much time left for the Hamburg-born player to get into title form before the French Open in Paris, which begins on May 26.