Tommy Haas will undergo hair and blood tests, while the International Tennis Federation (ITF) will investigate a claim that he was poisoned during Germany's Davis Cup semi-final defeat by Russia in Moscow in September.
"I want to find out if any poison can be traced or confirmed," Haas told Bild newspaper, which reported the 29-year-old would fly to New York on Friday for the tests.
Haas was beaten in straight sets on the opening day of the semi-final and was unable to play in the reverse singles on the final day because of gastro-enteritis. Russia won the tie 3-2 with victories in both of the reverse singles rubbers.
Alexander Waske, a doubles player in the beaten German team, was quoted in German media on Wednesday as saying an unnamed person had told him in Moscow that Haas had been poisoned.
Haas was quoted as saying by Bild: "I was shocked when Alex told me this but when I thought back about how bad I felt at the time I can imagine it's possible."
The ITF is investigating the matter, a spokeswoman told the DPA agency.
