World number two Carlos Alcaraz slumped to a shock straight sets loss to Chile's Nicolas Jarry in the semi-finals of the ATP Buenos Aires tournament on Saturday.
Defending champion Alcaraz, playing in his first tournament since losing in the Australian Open quarter-finals, was beaten 7-6 (7/2), 6-3 by his 28-year-old opponent.
Two-time Grand Slam champion Alcaraz had been hoping to reach his first final since losing to Novak Djokovic in the Cincinnati Masters in August and clinch a first title since Wimbledon in July.
Jarry, ranked 21 in the world, claimed his first win over Alcaraz in three meetings, wrapping up victory on a second match point after almost two hours on court.
"Third time lucky," Jarry said of his first win over Alcaraz. "Carlos is one of the best players so it means a lot, especially after the battles I've had a couple of days ago. It's been very tough physically, so I'm very happy to be able to come back.
"I didn't start very well and couldn't win points on his serve, but I came back little by little."
The Chilean didn't face a break point in the opening set and after the pair exchanged breaks in the first two games of the second set, Jarry claimed the decisive break in the eighth game.
Jarry will face Argentine wildcard Facundo Diaz Acosta, ranked 87, in Sunday's final of the clay-court tournament.