In the new rules, players must let drug-testers know their whereabouts for a period of 1 hour on EVERY DAY of the week - a measure which Nadal said makes players feel "like a criminal".
Andy Murray called it "draconian".
Previously players only need to keep anti-doping authorities informed of their whereabouts on 5 days a week.
After her 6-1, 6-2 victory over Karolina Sprem in the second round of the Paris Open last night (I slept half way through the match), Serena spoke to the press and backed Nadal over the drug-testing issue.
"It's too much," she said.According to the World Anti-Doping Agency (WADA) rule operates on a 'three strikes and out' basis over a period of 18 months.
"If I want to go on vacation to Barbados for one day, I shouldn't have to say I'm going to Barbados."
"I'm always complaining to my agents. I never tell people where I am, because I like to do my own thing."
Serena thinks she had already fallen foul of that rule!
"One time, I was out at dinner and someone turned up at my house to test me. I think I might even have got a strike."However Serena believes this move is to help make tennis drug-free and safeguard the sport's reputation.
"It's bizarre. I can't run home from dinner and get tested. It's very invasive."
"I think tennis is the purest sport out there," she said.
"We won't have problems in tennis that we have in other sports, so it's definitely a pure sport and that's the only upside to it."
(Via AFP, Image via opendfsuez.com)