Defending champion Cameron Norrie lost in straight sets to Argentine qualifier Mariano Navone in the semi-finals of the ATP Rio Open.
Norrie, 28, was aiming to win back-to-back titles at the Brazilian clay court tournament after defeating Carlos Alcaraz in last year's final.
But the British number one struggled in hot and humid conditions in Rio.
The 22-year-old Navone, ranked 113th in the world, won 6-4 6-2 to reach his first ATP final.
He will face compatriot Sebastien Baez after the world number 30 won 7-5 6-4 against another Argentine, Francisco Cerundolo.