Serena Williams is pushing back against unfair and unequal drug testing. The tennis star is speaking out after a drug tester showed up to her Florida home 12 hours earlier than the time she said she would be available, the Associated Press reported.

Williams has been drug tested this year more than other U.S. tennis stars, according to an initial report by Deadspin. She’s also been tested more times than the top five U.S. male stars, and had already been tested five times out of competition in 2018 as of last month. During a news conference ahead of a tournament at Wimbledon Sunday, Williams said it was frustrating to be targeted more than other players. She’s not opposed to drug testing, but said: “Just test everyone equally.”

The issue came up as a result of an incident at Williams’ home last month. On June 14, an unannounced USADA officer arrived at Williams’ residence for a drug test at 8:30 a.m. when she wasn’t home, Deadspin reported. Williams’ assistant let the officer into her home and he refused to leave unless she took a drug test. She ultimately did not take the test, and later complained to the Women's Tennis Association that she felt she was being unfairly targeted.

A Williams’ spokeswoman later reached out to Deadspin and called the test “invasive and targeted.” She added that Williams had never tested positive for illegal substances in her 23-year tennis career, even though she had been tested “four times more frequently than her peers.”

Williams said during the press conference that she was frustrated that she ultimately missed the drug test. According to the USADA, three missed drug tests over the course of 12 months result in a doping violation.

“I'm totally OK with testing and I encourage it,” Williams told the press, adding, “It's just about being equal and not centering one person out.”

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