In one of her latest tweets on Wednesday, seven-time Wimbledon champion Serena Williams pointed the finger at the US Anti-Doping Agency (USADA) over what she described as "discrimination."
Singling out random drug tests, the 36-year-old specifically bemoaned the fact that "out of all the players it's been proven I'm the one getting tested the most."
In a separate tweet, she also pledged to do her best "to have a clean sport."
The tweets came about three weeks after Williams complained about the way the USADA had treated her. According to the tennis star, an anti-doping official arrived at her residence early in the morning on June 14, some 12 hours before the time she previously agreed on.
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Earlier, USADA had confirmed that Williams had passed all of the five tests she underwent in June.
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In May, Williams also expressed frustration over the constant invasive behavior of the US anti-doping watchdog which she tweeted was "here again second time this week."