Spain's Alex Corretja has said he would join a player boycott if Greg Rusedski is banned over his positive drugs test.
Corretja, who claimed Rusedski is backed by most players, said: "I'd sign a petition for him."
There has been talk of a player boycott to support Rusedski, and Corretja said he would be willing to take part.
"This could happen to any player and I would like to have my fellow player doing that for me," he said.
However, Corretja said that the individual nature of tennis meant that a boycott was unlikely.
"This is tennis, everyone does what he wants, you have a lot of different interests and cultures working against each other," he said.
Rusedski, who tested positive for nandrolone, could be banned from the sport for two years if his mitigation is rejected by the Montreal tribunal chaired by Yves Fortier QC.
A verdict is expected imminently.
Rusedski pulled out of this week's indoor tournament in Rotterdam, fuelling speculation that he is expecting a negative outcome.
If the tribunal finds Rusedski guilty, the ATP will announce the verdict and the Briton will have 21 days to appeal to the Court of Arbitration for Sport.
If Rusedski is exonerated, it will be up to him to make the findings known and the ATP will have the option of appealing to CAS.
Rusedski's legal team argued at the Montreal hearing that his sample had the same "unique analytical fingerprint" as seven other positive tests which emerged last year.
Those seven players were cleared after the ATP were unable to prove that supplements handed out by their own trainers were not contaminated with nandrolone.
But the ATP counter-argued that Rusedski tested positive in July - two months after trainers had supposedly been told to stop using the supplements.