Williams, the top-ranked player in the women's game the and two-time defending Wimbledon champion, said she's not against out-of-competition testing in general but is opposed to no-notice testing.
"I don't think that's a good idea,'' she said. "I think there has to at least be a notice normally. I wouldn't let anyone in my house if I'm not expecting them. Showing up at the door - you kidding?''
"Actually that happened to me once,'' she added. "Someone tried to get in the development, doing a drug test. If I wasn't tested in the next two hours, I wouldn't be playing on tour. You know there's always someone at the gates trying to get in.
Normally I tell the gate, `Tell them Venus moved to Siberia some months ago.''
It was unclear when the episode occurred, whether it was in London or at her residence in Palm Beach Gardens, Fla., or whether those who showed up at her house were legitimate drug testers or impostors.
Asked about drugs in tennis, Williams said, "I don't think it's a factor at all.''