Andre Agassi has called on the ATP to apologise to Greg Rusedski if it was responsible for giving the Briton a contaminated supplement.
Agassi does not want a repeat of the Rusedski fiasco
Rusedski tested positive for nandrolone in July but was cleared of any wrongdoing by an independent tribunal.
The tribunal also said the ATP had probably accidentally given the British number two a contaminated supplement.
"Assuming there was cross-contamination there should definitely be an apology," said Agassi.
Agassi also said he sympathised with his tour rival for having his "entire life and career put on the line".
Rusedski's positive test is the latest in a line of similar ones on the ATP Tour.
Czech player Bohdan Ulihrach had his ban quashed in similar fashion - one of eight players to have escaped drugs bans in the last year because the ATP admitted its trainers could have been distributing contaminated substances.
And Agassi believes more has to be done to avoid any repeats.
"We've got guys being scared to drink out of a Gatorade bottle," said Agassi.
"We have to get to the bottom if it. The thought of somebody's livelihood, career or legacy to be ripped to shreds for an accident is a terrible thought.
"From a competitor's standpoint, the players have to count on two things: how extensive our testing is, meaning are we really getting to the bottom of are people cheating, and is there going to be some sort of due process that's fair?
"All we can really do is count on our governing body to see if it is dealt with fairly."