Djokovic advanced to the fourth round at the Australian Open on Friday with a straight-sets win over Radek Stepanek, but most of his post-match news conference was devoted to comment on Armstrong's doping admissions in a U.S. television interview with Oprah Winfrey.

I think it's a disgrace for the sport to have an athlete like this,'' Djokovic said.It would be ridiculous for him to decline and refuse all the charges because it has been proven. He cheated many people around the world with his career, with his life story.''

The Armstrong doping saga also raised questions over drug testing in tennis, and Djokovic said he supported the International Tennis Federation's current program.

At least from my perspective, it's really good,'' he said, outlining the current regime where tennis players have to give anti-doping authorities details of their whereabouts each day, in case they're required for out-of-competition testing.

It gives them an opportunity to test you. And you know it is the same for the other players,'' he said. At least from that point of view it's fair. And I have nothing against, you know, the anti-doping federation, association, testing me 10, 20, 30 times a year.''Having said that, Djokovic admitted blood tests which can detect the presence of EPO, a known oxygen booster in the blood which could help a tennis player cope better in long rallies and extended matches, have been a rarity for him lately.

He was asked to respond to reports that ITF records show that in 2011, only 18 blood tests were taken of the top players.Yeah, I wasn't tested with blood for last six, seven months,'' Djokovic said.It was more regular ... two, three years ago. I don't know the reason why they stopped it.''Regardless, Djokovic said he's confident of the integrity of tennis.I believe tennis players are (among) the cleanest athletes in the world,'' Djovovic said.So as long as we keep it that way, I have no complaints about testing.''

He admitted there have been complaints about the whereabouts'' rule where players have to let drug-testing authorities know where they plan to be _ either at a tournament, training, or even on holidays, so that testing can be conducted.

Frenchman Julien Benneteau, who lost his third-round match to Janko Tipsarevic on Friday, said Armstrong was a liar and a cheat for year'' and he has to pay.''

He said there was enough drug testing in tennis, but ``if there were more, that would be better.''I'm tested about 10-15 times a year,'' the No. 32-seeded Benneteau said. More controls. More blood testing, we don't have much of that.'`We can't be naive. No sport is sheltered from it,'' he said. In tennis it's not just physical. It's technical and mental. But we still need to stay vigilant.'' Djokovic's Serbian Davis Cup teammate Janko Tipsarevic said he'd been subjected to doping tests in out-of-competition periods, and as far away as Africa Testersactually came to Kenya to test me,'' he said.I wasn't going to Kenya to hide from anti-doping. I was actually doing my pre-season there.''

Tipsarevic agreed it was not cool'' for Armstrong to beCheating the sport and cheating so many people in the sport and so many people around him, believing that what he did actually did it on a clean and regular way.''