An anti-doping test carried out in 2006 revealed abnormally high levels of testosterone in Dutch tennis player Robin Haase, press reports in the Netherlands revealed on Friday.
Haase, 26, explained in the daily Volkskrant that, after undergoing the test, he received a letter from the ATP advising him "to get a lawyer" and indicating that he would have to undergo three more tests in the following two weeks.
However, according to Haase, the letter also indicated that "the abnormal level could very well be natural".
During the following controls, "every time my levels were the same, and I have not heard anything about it since," he added.
"I have never been afraid of being pursued for this positive test as it was established that I hadn't been doping.
"I have been tested a dozen times in 2013, but I think controls in tennis need to be better targeted."
Haase is currently ranked 43rd in the world, although he did reach a high of 33rd in July 2012.