London: Concerns over tennis' lack of doping safeguards deepened on Sunday when Roger Federer, president of the Association of Tennis Professionals' player council, revealed that he was not being drug tested as much now as he was back in the mid-2000s.
Federer's comments came on the heels of Andy Murray's calls for more testing to be carried out, and they reflect the lack of rigour in the sport's defences.
"I feel I am being tested less now than six or seven years ago," said Federer, who will open his ATP World Tour Finals campaign on Tuesday against Janko Tipsarevic of Serbia.
Federer did not have the exact statistics of his own tests to hand, but ITF documents show that he was tested between five and nine times in 2011.
The equivalent � if somewhat vague � figure from 2010 was "more than eight".
"Whatever number it is, I do not think it is enough," Federer said.
"I think they should up it a little bit, or a lot. It is vital that the sport stays clean. We have had a good history in terms of that and we want to ensure it stays that way."