Nadal won gold in the Beijing Olympics in 2008 but missed the London Olympics with an injury. Despite being asked about it repeatedly, he's staying away from talking about the Rio Olympics that open in six months.
"The Olympics is a very important event, a very special one, and I'm going to try my best when the Olympics arrive," Nadal said. "But for now I'm playing the ATP tournament in Rio. That's the most important thing for me."
Not much will faze Thiem in this week's Rio Open.
He beat Nadal -- the king of clay -- last week in the semifinals in Buenos Aires, and then won the event for his fourth clay-court title.
"Both things gave me a lot of confidence, but after the match with Nadal I wanted to give everything to win the tournament," the 22-year-old Austrian said. "The win against Rafa would have been worth only half if I had lost the final."
Last year's finalist, Fabio Fognini -- who handed Nadal a first semifinal defeat on clay for 12 years in 2015 -- is safely through to the second round after beating British No.2 Aljaz Bedene 7-5, 6-3.
Pereira's early loss is a blow for the women's side of the combined WTA-ATP event on outdoor clay. She is only ranked No. 43 but gave local organizers a hometown favorite.