Rafael Nadal failed to reach his 100th ATP final after losing to Pablo Cuevas in the Rio Open semi-finals - his second last-four exit in a week.
The 14-time Grand Slam champion and top seed saved two set points in the second set, but lost 6-7 (6) 7-6 (3) 6-4 to unseeded Uruguayan Cuevas.
"I lost an opportunity," Nadal said. "I have to accept it and keep working to try to change the dynamic."
World number 45 Cuevas will meet the unseeded Guido Pella in the final.
The Argentine won 6-1 6-4 against Austrian fifth seed Dominic Thiem, who beat world number five Nadal in the last four of the Argentina Open last week.
The consecutive semi-final defeats for Nadal continue a disappointing season, which began with a first-round loss to Fernando Verdasco in the Australian Open.
"I didn't win a title, so it wasn't a positive two tournaments," the 29-year-old Spaniard said. "I had my chances in both but I just have to look forward."
Italy's Francesca Schiavone, 35, won her first title for three years with a 2-6 6-2 6-2 victory over American Shelby Rogers.