Serena Williams is distinguished as one of the best athletes to ever live. She has broken multiple tennis records that for many has enshrined her as the GOAT. However, Williams is also distinguished by being the most frequently drug tested top tennis player.

In response to an article that revealed Williams was drug tested more than any other male or female players, Williams stated at a Sunday conference, “I never knew that I was tested so much more than everyone else… Until I read that article I didn’t realize it was such a discrepancy with me as well as against the other players that they listed, at least the American players — both male and female.”

The revelation came after a particular incident in 2018, when a U.S. Anti-Doping Agency (USADA) officer came to Williams’ Florida home for an unannounced 8:30 am drug test on June 14, when Williams was ranked only 449 in the world. Williams was not home and the officer refused to leave until she was tested. Williams contacted the Women’s Tennis Association (WTA) and the USADA to remove the officer as she felt it was “unfair targeting.”

In 2018 alone, excluding the surprise June 14 test (which did not happen), Serena Williams has been tested a total of five times. According to the USADA database, the number of tests Williams received is more than twice that of any other top five American male or female players.

The WTA’s CEO, Steve Simon told Deadspin, “I received a text from Serena and called her back and left a message. She shared with me some concerns and questions she had about an out-of-competition drug test.”

Simon shared it’s also “not uncommon” for athletes to contact him about international and out-of-competition tests as it is always an “education process.”

In response, the USADA released the following statement:

“We talk with athletes all the time about clean sport and our programs. We spoke with Serena recently about a recent test mission. Serena has been supportive and engaged with our program, and she is in good standing with our program. As our website indicates, Serena has been tested five times out of competition by USADA so far in 2018, all of which she has passed. Our recent conversation was a good one just like the many other times we have spoken with her.”

Williams’ team responded, “Over her 23-year career in tennis, Serena Williams has never tested positive for any illegal substance despite being tested significantly more than other professional tennis players, both male and female – in fact, four times more frequently than her peers. She has vocally supported, respected and complied with USADA testing throughout her entire career. While she willingly continues to submit to testing, there is absolutely no reason for this kind of invasive and targeted treatment.”