Rafael Nadal says he's not afraid of the Zika virus as he travels to Rio de Janeiro for the Rio Open. That may be due to the fact that he's still too scared about his play.

Another poor result could result in Nadal's demise in tennis.

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He will travel to Rio at a time when Brazil is at the center of an outbreak of the Zika virus, BBC.com reported. The World Health Organization has declared the virus a global public health emergency.

"I'm going out at night. I'm not scared. I'm not worried about this. If it happens, it's bad luck."

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Nadal's bad luck instead has reflected on the court, again, as he lost in the semifinals of the Argentina Open to Australian Dominic Thiem, 6-4, 4-6, 7-6, failing to defend his 2015 title and losing on his favored surface, clay.

"It's too early to make an assessment," Nadal said, according to Tennis World USA via International Business Times. "Today I was in the position to play another final, I played the first final of the year in Doha and [at Argentina Open] I did not succeed. I go to Rio with the goal to improve and to reach it there."

Nadal's optimism, however, has fallen on deaf ears as his slump has extended into its second year.

He may not yet be concerned about his fleeting game, but others sure are.

Calling this week a "massive week" for the Spaniard, Sky Sports' Barry Cowan wonders what another loss will do to Nadal's psyche.

"When you lose in the manner that Rafa lost a few days ago, lost his nerve at important stages, which was something which was happening with regularity in the beginning of last year," Cowan said.

"But crucially he lost to someone in Dominic Thiem who is going to be a very good player, who is young, who doesn't have the same mental baggage as a lot of players who are currently on tour and have lost to Nadal, three, four times.

"A massive week for Nadal and I almost go to say I think he's got to win this week, I really do."

Cowan isn't the only one sounding the alarm on Nadal's future.

"Even clay has been tough on Rafael Nadal's quest to return to prominence," Bleacher Report indicated. "He lost in Argentina, but this time it did not look like an upset. Other players like Dominic Thiem are strong, hungry and competing for titles from South America to Memphis to Rotterdam."

Until his quarterfinals loss to Novak Djokovic at the French Open, Nadal was considered the best player on clay, perhaps ever.

Without that fallback, Nadal is staring at the beginning of the end.

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