BUENOS AIRES • Defending champion Rafael Nadal suffered another setback on Saturday when he squandered a match point on his beloved clay before losing 4-6, 6-4, 6-7 (4-7) to Austria's Dominic Thiem in the Argentina Open semi-finals.
Top seed Nadal, playing on his favourite surface, finally wilted in the 32 deg C heat in Buenos Aires after 2hr 50min on court against Thiem, the world No. 19.
"It was a tough match. I had a chance to win and missed it but Thiem played well," said Nadal, whose clay-court title total remains on 47.
"I'm not worried. I just lacked consistency and need to make fewer unforced errors, but that's nothing."
He now heads for Rio de Janeiro, where he will again be top seed this week. He is expecting similarly gruelling conditions in the Olympic host city.
"I struggled a bit to adapt to the extreme conditions here. I felt more tired than usual. I know that in Rio de Janeiro it's not going to be better, so I must continue to adapt," said the Spaniard, the Rio Open champion in 2014.
Nadal, in his first tournament since his shock first-round exit at the Australian Open, dropped serve in the ninth game of the opener to allow 22-year-old Thiem to serve out for a one-set lead.
The 29-year-old fought off a break point in the seventh game of the second as the big-hitting Thiem, the youngest member of the world top 20, threatened to run away with the contest.
But the 14-time Major winner, who won the pair's only other meeting at Roland Garros in 2014, made the most of his lifeline to break in the 10th game to level the semi-final.
Thiem nipped ahead for 2-0 in the decider. But back came the world No. 5 to level at 2-2 before Thiem saved a match point in the 10th game.
In the tiebreaker, however, it was Thiem who proved the stronger, stretching to a 6-1 lead.
Nadal saved three match points but the fifth seed held his nerve.
"Bamos defeated Vamos!," wrote Thiem on his Facebook page. "I cannot believe it! I fought off a match point and managed to gain a win over one of the best clay courters. To beat such a player is insane, I will never forget that moment in my life."
He was set to face another Spaniard, Nicolas Almagro, in yesterday's final.
Almagro defeated his second-seeded compatriot David Ferrer 6-4, 7-5.