Tennis is one of the world's cleanest sports in terms of drug abuse -- if not the cleanest, Andre Agassi said on Tuesday.

The spotlight in Sydney has been on Greg Rusedski after the Briton's admission last week that he had tested positive for the banned steroid nandrolone.

But Agassi, one of the biggest names in sport, told reporters ahead of an invitational tournament in Kooyong that he is convinced tennis does not have a problem with doping.

"Well, one of the things we can say for sure is our sport is the leading, if not the top, sport in drug testing in both its intensity as far as what they test for.

"It's a very extensive list, probably more extensive than any other sport, and how often they test.

"Last year I played 13 tournaments. I was tested (via a) urine sample 11 times, I was tested (via a) blood sample eight times, which includes three out of competition testings.

"It's not possible to get more aggressive with the goal of maintaining the integrity of our sport," he added.

Rusedski last week admitted he tested positive during the RCA Championships in Indianapolis last July but said he would be cleared of any wrongdoing at a hearing in February.

World number four Agassi applauded Rusedski and the ATP's efforts to get to the bottom of the issue.

"We need to get to the bottom of something that's crucial to our integrity and that's going to require everybody accepting responsibility and it's going to require keeping useless... and irresponsible quotes out of the headlines.

TESTED REGULARLY

"I can't speak for his (Rusedski's) situation because I don't know it. Again, I think that the right thing to do for Greg, as well as the governing bodies, is to be responsible and diligent in their efforts to get to the bottom of it."

World number one Andy Roddick, who is also playing in the Kooyong Classic that starts on Wednesday, agreed with his fellow-American that the ATP is doing a good job keeping tennis drug free.

"As Andre said earlier, we are tested very regularly and for an extremely extensive list of things so I definitely feel like if I'm playing someone on the other side of the net and they haven't been caught or publicly announced that it's a very fair match," he told reporters.

Roddick added that he had been tested "17 or 18" times last year.

Rusedski has said that nandrolone has been detected in varying degrees in 47 players. The ATP, the governing body of men's tennis, admitted in July that its trainers may have inadvertently provided the drug through adulterated tablets.

But Rusedski is believed to be the only player to have exceeded the allowable nandrolone limit since the ATP's July announcement.

The British player is free to play on the ATP circuit pending his appearance before the independent anti-doping tribunal in Canada next month.

EFFECTIVE SYSTEM

Agassi said he was happy with the procedures in place to catch drug cheats.

"I can say that our system is set up to expose... and it's as effective, if not the most effective, system in sport.

"As players, we need to be able to count on the fact that there's a due process.

"If we feel like it's possible for a player's reputation and career to be slung and sort of dragged through the mud and tarnished in the way that in this particular example Greg is going through, at the possibility of him being innocent, that would leave us in a very bad place because we would have to sit back wondering `gees, what if something really unfair happened to us?', so the process that is set in motion is one that I think the players believe in strongly.

"Not only are we tested often, we are tested in a way that brings to light everything in your system so we also have a process that's set up to make sure that everybody is treated fairly, and that's something that the players can sit back and actually feel good about.

"To see Greg compete now is one of the things that allows us to know that nobody is going to get treated unfairly and that's an important part of this."