The governing body of men's tennis, ATP, said it would not appeal against the decision of its own tribunal to clear Britain's Greg Rusedski of failing a drugs test.
Rusedski was cleared of doping offences earlier this month after the tribunal found the ATP could have been responsible for his positive nandrolone test.
A three-man panel appointed by the ATP exonerated the Canadian-born 30-year-old, saying that the governing body itself had probably provided contaminated supplements to the player.
Rusedski was the eighth player in as many months to be exonerated of culpability for ingesting the drug because it was found to come from one of the ATP's own sources.
The ATP stopped their trainers handing out the electrolyte tablets in May but that does not appear to have eliminated the problem.
The ATP have set up a task force on supplements to try to find ways players can safely take supplements to replace vitamins and minerals lost during matches.