"Tennis does a good job of testing from my experience," said 20th-ranked John Isner, the American number one, yesterday. "Tennis as a whole, I do feel, our sport is clean."
The topic has drawn attention after Troicki was banned for 18 months after allegedly refusing to submit a blood sample to a tester and Cilic reportedly tested positive at an April event in Munich.
Troicki, ranked 53rd, said he was assured he could skip the blood test without punishment.
"Our doping system is extremely tough," said American Mardy Fish.
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"We do get updates. We get a lot of information. There are things constantly coming through e-mails about player regulations, regulated substances."
Asked if he thought players were not well informed about doping regulations, Fish said, "That wouldn't be my experience, no. I like to take that pretty seriously."
Isner said the topic has not resonated with players, saying, "As far as talk in the locker room, there hasn't been any at all.
Isner said he was once random tested twice in the same morning.