Tim Henman has told BBC Sport that his gut feeling is that Greg Rusedski is "clean", despite his Davis Cup team-mate's positive drugs test.
By Jonathan Overend
BBC tennis reporter
"I take my hat off to him the way he's come down here and has played some really good tennis," said Henman.
"My gut feeling is that he wouldn't do something like that so that's why it [the nandrolone mystery] puts a lot of uncertainty into players' minds."
Rusedski, meanwhile, reiterated that he "knows" he is innocent.
Rusedski was in an upbeat mood after a session with Thai number one Paradorn Srichaphan, and said: "I've had wonderful support.
"The fans were right behind me in Sydney.
"I'm not going to hide, this is the situation I'm in and this is what I love to do - play tennis.
"A lot of British fans were wishing me luck saying, 'we're sorry this has happened to you but we're sure everything will be fine'.
"I've had that in the locker room and from the fans so I can't ask for more.
"Deep down I know I am innocent and that's the most important thing in the whole issue."
Rusedski has unluckily drawn Albert Costa, the former French Open champion, in the first round.
If he causes an upset, the British number two could face the dangerous Australian Wayne Arthurs next.
Henman, in a more favourable section of the draw than his compatriot, plays Jean Rene Lisnard of France, a player he beat on their only previous meeting in Adelaide 2000.
When news of Rusedski's failed drugs test first came through, Henman issued a short statement expressing "surprise".
Now he has had a week to digest the news, Henman is urging the public to reserve judgement until the hearing takes place.
His tone was supportive towards his compatriot.
"It puts you in a difficult position because the liability is with the athlete so you do have to be extremely careful and take responsibility. Hopefully it will all be resolved on 9 February."
"If you're going to take something it would be a massive risk because we are tested so frequently."