Dominic Thiem booked his spot in the final of the Argentina Open with a surprise semi-final win over Rafael Nadal on Saturday.
Many expected reigning champion Nadal to ease through into the decider but 22-year-old Thiem showed tremendous fight in his 6-4 4-6 7-6 (7-4) victory over the top seed.
The Austrian fifth seed hit nine aces to Nadal's two in the match that lasted just under three hours.
While both won three break points each, Thiem was more clinical on his second serve, winning 61 per cent of points compared to Nadal's 47.
"It was a tough match. I had a chance to win and missed it but Thiem played well," Nadal said.
"I'm not worried. I just lacked consistency and need to make fewer unforced errors, but that's nothing."
Thiem will meet Nicolas Almagro in Sunday's final after the Spaniard got past compatriot David Ferrer in straight sets.
Ferrer showed signs of fatigue having finished off his quarter-final tie against Pablo Cuevas earlier in the day after their match was suspended overnight due to rain.
Three-time winner Ferrer was leading 4-2 in the first set before the game was suspended, going on to complete a 6-4 1-6 6-3 win over the Uruguayan.
However, the 33-year-old could not back it up against a fresher Almagro, going down 4-6 5-7 in just under two hours.
Almagro saved all five of Ferrer's break points on his way to victory as he looks to win a second title in Buenos Aires.