Rafael Nadal failed to convert three match points as he fell to a quarter-final defeat against Australian Jordan Thompson at the Brisbane International.
Nadal, 37, went close to sealing a straight-set victory but lost 5-7 7-6 (8-6) 6-3 to 29-year-old Thompson.
It was Nadal's third match since returning to action after almost a year out with a hip injury.
Thompson will face world number 14 Grigor Dimitrov in the semi-finals on Saturday.
After wins over Dominic Thiem and Jason Kubler earlier this week, Nadal faced by far his toughest test yet of his comeback against Thompson, ranked 55th in the world.