Novak Djokovic said a majority of players believe favouritism is at play in the tennis anti-doping system.
Rather than face the prospect of a lengthy ban, with a decision expected by the end of the year, World No 1 Jannik Sinner accepted the three-month suspension which will allow him to return before the French Open.
The world No. 1 said the "mental part" of his game was especially important in his run to the US Open title this year.
'I guess only the top players' images matter. I guess only the independent tribunal's opinion on the top players is taken as sound and right.'
'Irresponsible' Djokovic panned for Adria Tour misadventure.
While tennis is a lucrative sport for those at the top -- the 2020 Australian Open singles champions each took home A$4.12 million ($2.52 million) -- those in the lower echelons often struggle to make ends meet.
Second seed Garbine Muguruza, bidding to add the Wimbledon crown to her French Open title, was sensationally beaten in the second round on Thursday by Slovakian qualifier Jana Cepelova 6-3, 6-2 in the shock of the tournament so far.