Three-time French Open champion Gustavo Kuerten called for severe punishment for any players caught match-fixing, but believes they are isolated cases.
The Brazilian, winner at Roland Garros in 1997, 2000 and 2001, said the sport's culture made him believe corruption was rare.
The BBC and BuzzFeed News revealed details of a joint investigation, alleging that tennis authorities had failed to act upon repeated warnings regarding claims of match-fixing involving several players on the professional circuit.
In a subsequent news conference, ATP executive chairman and president Chris Kermode said the governing body of men's tennis "absolutely rejects any suggestion that evidence of match-fixing has been suppressed for any reason or isn't being thoroughly investigated".
Kuerten said it was an issue that needed to be dealt with, but also feels it is rare.
"This episode is very sad. Throughout my career I have never been harassed, but this subject haunts tennis for a long time," he wrote on Instagram.
"For me, match-fixing, as well as doping, represents corruption within the sports environment that needs to be banned.
"Through the years I've been on the circuit, the ATP always fought this case very seriously.
"This subject is extremely worrying because it compromises the essence of the sport, the fair play, the respect for rules.
"Because of the decency and justice cultivated by the tennis world, I believe them to be isolated cases where the punishment should be severe."