London - Serena Williams demanded fair treatment from US doping chiefs after the former Wimbledon champion was shocked to be subjected to a series of tests in June.
Williams arrived at Wimbledon this week on the heels of a report that she was unhappy at excessive targeting from US Anti-Doping Agency drug testers.
A Deadspin article revealed Williams' anger about an unannounced test in June where the tester refused to leave her Florida house.
The tester visited outside Williams' specified "whereabouts window" and found her not at home.
No athlete is obliged to comply with a testing visit if it is not made during the 60-minute window for which the athlete identifies their whereabouts in advance each day.
"I guess they decided it was a missed test, which really doesn't make sense. Anyone would logically think that I would have to be home 24 hours a day, or I get a missed test," Williams told a press conference on Sunday.
"You only get three missed tests. For me it's a little frustrating. How can I have a missed test when it's nowhere near the time I should be there?
"It's really disappointing, shocking. I was just like: 'That's just weird'."
The incident was made public after WTA chief Steve Simon was overheard leaving a message on Williams' answerphone at an airport.
Williams, preparing for the start of Wimbledon on Monday, made it clear she didn't expect to have been tested so often this year.
"It's unfortunate but I guess when you're in my position, you mention my name, people overhear things and they want to tell the press," she said.
"I actually thought the article was interesting. I didn't know I was tested so much more than everyone else. I do know I'm always getting tested all the time, no matter where I'm ranked.
"I didn't realise it was such a discrepancy, at least with the American players. It would be impossible for me not to feel some sort of way about that."
Concerned at being tested more than her fellow American players, seven-time Wimbledon winner Williams revealed she had spoken to USADA chiefs.
The 36-year-old said she was tested five times on June, compared to one or none from some of her compatriots.
Athletes returning from a long absence are often the subject of repeated drug tests, as they are seen as part of a higher-risk category than athletes in the flow of regular competition.
But, calling for equal treatment, the 23-time Grand Slam winner said: "I had a conversation with the lead guy with USADA. I think he was mentioned, as well.
"How is it I'm getting tested five times in June? It's only June, I've been tested five times. I'm okay with that.
"Literally verbatim, I said, I'm going with that, as long as everyone is being treated equally. That's all I care about.
"I despise having people in our sport that aren't being honest. I'm totally okay with testing and I encourage it.
"If that's testing everyone five times, let's do it. Let's be a part of it. It's just about being equal and not centring one person out.
"Just due to the numbers, it looks like I'm being pushed out. Just test everyone equally."
Roger Federer, the reigning Wimbledon men's champion, backed Williams' claim that testing procedures need to be overhauled.
"I've had a lot of testing the last month. I think I've had seven tests. Where I live in Switzerland, the tester lives in the same village, so it's very convenient!" he said.
"But I mentioned many times in Dubai I've hardly ever been tested, which has been quite disappointing. To honest, in the 15 years I've been there, it's been one test.
"Maybe that's the part I don't like so much, the inconsistency of the places where they test.
"What's important is these people are professional, they treat you like humans, not like criminals.
"I understand the frustration. I have it, too."