Tennis' governing bodies rejected claims they covered up or ignored evidence related to match fixing in the wake of an investigation that said grand slam winners were among a group of 16 players "who have repeatedly been reported for losing games when highly suspicious bets have been placed against them."
No names were mentioned.
The documents -- reportedly handed over by whistleblowers -- also allegedly show gambling syndicates in Russia and Italy profited by betting on games believed to have been fixed, according to the Buzzfeed and BBC reports.
The tennis authorities, comprised most notably of the men's ATP Tour, women's WTA Tour and the international ITF, "absolutely reject any suggestion that evidence of match fixing has been suppressed for any reason," said in a statement released in Melbourne, site of the Australian Open.
Match-fixing scandals have rocked football's Serie A in 2006 and international cricket in 2010 but no major cases have led to penalties in top-tier tennis. So far, there have been 18 "convictions," as ATP head Chris Kermode put it, and six lifetime bans stemming from the Tennis Integrity Unit, which was formed in 2008.
The highest profile investigation conducted by the ATP revolved around a match played a year earlier in Sopot, Poland, between former world No. 3 Nikolay Davydenko and Martin Vassallo Arguello. Despite suspicious betting patterns, neither player was formally charged.
"A yearlong investigation into the Sopot match in 2007 found insufficient evidence," Kermode said in a press conference prior to the statement. He added: "The investigators hit a brick wall and it just wasn't possible to determine who the guilty party was in relation to this match."
Indeed, players under investigation are under no obligation to hand over potentially incriminating evidence.
"We can demand their phones and laptops and iPads," said TIU director of integrity Nigel Willerton in the press conference. "Obviously they have to consent to give them."
One player who didn't cooperate, Ivo Klec, was given a two-year ban
"We also work closely with law enforcement, because the tennis anti-corruption program does mirror criminal offenses basically, but we are not law enforcement," said Willerton. "Whereas they could arrest people and seize those items, we cannot."
A former senior official with the ATP said the risk of match fixing is very high.
"The ATP, ITF, WTA need to really redouble their efforts and redouble their resourcing to ensure that everything possible is being done to protect the competition," Richard Ings told CNN's "World Sport."
'Difficult to catch everyone'
Top-ranked men's player Novak Djokovic said an approach was made to his team by match fixers in 2007 but was immediately rejected. He called some of the report "speculation."
"Of course, there is no room for any match fixing or corruption in our sport," the defending champion said in his press conference after beating Hyeon Chung in his opening match Monday. "We're trying to keep it as clean as possible. We have, I think, a sport (that has) evolved and upgraded our programs and authorities to deal with these particular cases.
"I don't think the shadow is cast over our sport. In contrary, people are talking about names, guessing who these players are, guessing those names. But there's no real proof or evidence yet of any active players, for that matter. As long as it's like that, it's just speculation. So I think we have to keep it that way."
Djokovic confirmed that his support team was offered $200,000 for him to lose a first-round match in St. Petersburg almost a decade ago -- but he did not play at that tournament.
"I was approached through people that were working with me at that time, that were with my team. Of course, we threw it away right away," the Serbian said.
"It didn't even get to me -- the guy that was trying to talk to me, he didn't even get to me directly. There was nothing out of it.
"Unfortunately there were some -- in those times, those days -- rumors, some talks, some people were going around. They were dealt with. In the last six, seven years, I haven't heard anything similar."
Women's No. 1 Serena Williams said if match fixing was taking place, she was unaware of it.
"I'm kind of sometimes in a little bit of a bubble," she told reporters after her first-round victory over Camila Giorgi.
Paul Annacone, the former coach of Roger Federer and Pete Sampras, believed elite players didn't need to participate in match fixing to make good money.
"I would be shocked if it was prevalent with top players because they are earning such a good living and making their professional progress so well that why would you risk that much?" he told CNN.com.
Djokovic pocketed $21 million in 2015, while world No. 100 Daniel Gimeno-Traver of Spain made $350,000
-- a good wage even after subtracting expenses such as flights, hotels and support personnel.
Due to the sheer volume of matches in professional tennis, it's difficult to catch everyone, according to Kermode.
Players in the second-tier Challenger system and third-tier Futures may be targets because of how little they make. The BuzzFeed and BBC investigation said players could be offered $50,000 or more per fix.
"There are nearly 21,000 active professional players and over 2,100 officials, playing and officiating in over 1,500 tournaments in 80 countries around the world," said Kermode. "The vast majority of these individuals are good people of high integrity.
"Unfortunately there is always a minority who seek personal gain from corrupt activity. Those individuals will continue to be subject to investigation by the TIU and disciplinary sanctions."
Annacone added: "It would surprise me at the top of the game. It wouldn't surprise me so much for lower-level players that are trying to make a living. I could see lower-level players being tempted."
When that happens, the players just have to do the right thing, said doubles No. 1 Marcelo Melo.
"If I was a Futures player I wouldn't do it because I don't think this is right," he told CNN.com. "But some people don't think like that. You have to get your money the right way."