Nadal believes anti-doping regulations are too strict
World number two Rafael Nadal has reiterated his criticism of anti-doping regulations in the wake of bans handed to Xavier Malisse and Yanina Wickmayer.
The Belgian pair fell foul of the rule requiring players to tell anti-doping authorities where they will be for one hour of every day over three months.
"I am the first who wants a clean sport but the way [controls] are being done is, in my opinion, not right," he said.
"It's too much to have to say where you are every day of your life."
Nadal, like Britain's Andy Murray, has been a vocal critic of the World Anti-Doping Agency's "whereabouts" rule, which was introduced on 1 January 2009.
Under the new rules, athletes must make themselves available to testers for one hour a day, between 0600 and 2300, three months in advance.
I have confidence in my colleagues and in other players. I always believe they're clean
If an athlete fails to be in the specified location on three occasions in an 18-month period, they incur an automatic ban.
Malisse and Wickmayer were both given one-year bans by the Flemish Doping Tribunal in Belgium for falling foul of the rule.
They have both announced their intention to appeal to the Court of Arbitration for Sport, although Malisse said he may struggle to afford the costs involved.
Fellow Belgian Kim Clijsters described the punishments as "extremely harsh".
Nadal added: "I'm always going to side with the players and defend the players.
"I have confidence in my colleagues and in other players. I always believe they're clean. Until the results tell me otherwise, I'm going to defend my friends."
The bans for the Belgian pair were announced shortly after Andre Agassi revealed in his autobiography that he tested positive for crystal meth in 1997 and lied to the ATP in order to escape a ban.
Nadal and world number one Roger Federer have both expressed their shock that Agassi was able to avoid punishment by claiming his drug use was accidental.
But two-times Grand Slam champion Marat Safin believes Agassi has betrayed their governing body and should even consider giving his titles and prize money back.
"I'm not defending the ATP, but what he said put it in a delicate position," the Russian, who will retire at the end of the season, told French sports paper L'Equipe.
"The ATP allowed him to win a lot of tournaments, a lot of money. It kept his secret. Why does he need to be so cruel with it?
"If he is as fair play as he says he is, he has to go to the end. You know, the ATP has a bank account and he can give the money back if he wants."