On a day of extended drama and fevered speculation, Novak Djokovic spoke in depth for the first time about being offered $200,000 (£140,000) to fix a match 10 years ago and Roger Federer, the game’s most venerated player, called the latest allegations, to be aired on the BBC on Tuesday night, “far-fetched”.

Djokovic and Serena Williams, the top-ranked players in the men’s and women’s game, were adamant there was no wrongdoing beyond minor incidents on the edges of the sport, and pointed out that no hard evidence had been produced.

The BBC, which conducted a long investigation in company with Buzzfeed News, has claimed an unnamed grand-slam winner was under suspicion, and that eight players who have been investigated during the past decade are in the main draw here in Melbourne.

They say they have a “cache of documents” stretching back to 2007 that expose “widespread suspected match-fixing at the top level of world tennis, including at Wimbledon. Over the last decade, 16 players who have ranked in the top 50 have been repeatedly flagged to the Tennis Integrity Unit (TIU) over suspicions they have thrown matches.”

After seeing off the exciting young Korean Hyeon Chung in three quick sets on the first day of the 2016 Australian Open, the defending champion Djokovic said: “I’ve heard about the story and I read that there were a couple of players mentioned who are not active any more, talking about the matches that have happened almost 10 years ago. Of course, there is no room for any match-fixing or corruption in our sport. We’re trying to keep it as clean as possible. We have, I think, a sport that has evolved, and have upgraded our programmes and authorities to deal with these particular cases.

“I don’t think a shadow is cast over our sport. People are talking about names, guessing who these players are. 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.”

He spoke too about an incident in 2006 when it was alleged he had been offered $200,000 to throw a first-round match in St Petersburg, a tournament he did not eventually attend. “I was not approached directly,” he said. “Well … 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. 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, rumours, some talks, some people were going around. They were dealt with. In the last six, seven years, I haven’t heard anything similar. I personally was never approached directly, so I have nothing more to say about that.”

Facebook Twitter Pinterest Serena Williams said she was not aware of matches being fixed. Photograph: Mast Irham/EPA

Pressed further, he went on to say: “It made me feel terrible because I don’t want to be anyhow linked to this. Somebody may call it an opportunity. For me, that’s an act of unsportsmanship, a crime in sport, honestly. I don’t support it. I think there is no room for it in any sport, especially in tennis.

“I always have been taught and have been surrounded with people that had nurtured and, you know, respected the sport’s values. That’s the way I’ve grown up. Fortunately for me, I didn’t need to, you know, get directly involved in these particular situations.”

Before what might or might not be explosive revelations on the BBC on Tuesday night, there was a sense here after the first day of the tournament that the only way these reheated claims will damage the sport is if players are named. Federer added an unusually angry voice to the story when he faced the media shortly after a routine win over the Georgian Nikoloz Basilashvili. He was particularly upset by the claim that one of the players under suspicion was a grand slam champion. “I mean, it’s, like, who, what? It’s, like, thrown around. It’s so easy to do that,” he said in a rare state of agitation.

“I would like to hear the name. I would love to hear names. Then at least it’s concrete stuff and you can actually debate about it. Was it the player? Was it the support team? Who was it? Was it before? Was it a doubles player, a singles player? Which slam? It’s so all over the place. It’s nonsense to answer something that is pure speculation.

“It’s super serious and it’s super important to maintain the integrity of our sport. So how high up does it go? The higher it goes, the more surprised I would be, no doubt about it. Not about people being approached, but just people doing it in general. I just think there’s no place at all for this kind of behaviour in our sport. I have no sympathy for those people.

“Under my watch [as chairman of the ATP Player Council], we discussed it early on. But I actually never heard about it until it was brought up at a player meeting.. Came totally from left field. Had no clue what it was about. Didn’t know it existed.

“I hadn’t been approached. But it doesn’t matter whether I’ve been approached or not; I haven’t. It’s a bit far-fetched.

“Betting happens all across the world in all the sports. The players … need to make sure the integrity of the game is maintained because, without that, why do you come and watch this match tonight or any match? Because you just don’t know the outcome. The moment that gets taken away, there’s no point any more to be in the stadium. That’s why it’s super important to keep it clean.”

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According to a senior source, it is highly unlikely any players will be named on the BBC. “I’d be surprised,” the source told the Guardian, “as they will potentially be in for huge libel issues. Unless they have evidence against them, they are on tricky ground.”

For most of the day, interest switched from the courts to the press conference room, where administrators and players were quizzed as if on a conveyor belt of suspicion and doubt. Marin Cilic, who won the US Open two years ago and progressed without fuss into the second round here by beating Thiemo de Bakker 6-7, 7-5, 6-2, 6-4, said he had never been asked to cooperate with match-fixers. “No, I never had any of that kind of situation and, even if I did, I would come forward to the ATP, to the people who are working for that.”

Did the scattergun speculation damage players across the board? “No, not for me. I know I am very far away from betting even though it is very popular in Croatia. A lot of people like to gamble, but I know I am safe, that I don’t do any betting. That’s very far away from me.

“I have big faith [in the game’s administrators]. They are the guys doing their job and I guess they are going it well. They know what they need to do to keep the sport the way it is. I have no idea [if match-fixing exists]. I hope not. That’s more a question for the integrity unit. But no, I don’t think it exists, not at this high level.”

Maria Sharapova, after beating Japan’s Nao Hibino in two quick sets, said she hoped players would not be tempted to fix matches, whatever their ranking or income.

“Honestly, I really hope not,” she said. “To me the sport has always meant a lot more than money. I know that the more successful you are and the more matches you win, the more prize money you will receive. But, ultimately, that’s never been my personal driving factor in the sport. There’s just so much more on the line. There’s the competitiveness. There’s the challenge of being better. There’s playing in front of thousands of people, playing you against somebody across the net and you trying to win that match. When you’re out there, it’s not about money.”

Gilles Simon, who beat Vasek Pospisil in four tight sets to reach the second round, is a member of the ATP Player Council. He said later: “It is a bit like the anti-doping – you feel like someone is dropping a bomb on the first day of a slam. Is there any evidence? Say it and everyone will be happy to know and to take action. But to do that? I don’t really understand. We have the TIU. We know it is important and can damage our sport a lot, so we are paying attention. There is not much to say because there was not much in it.” Williams, talking after her tougher than expected 6-4, 7-5 win over the Italian Camila Giorgi, said: “Yeah, I just heard about it today, just as a warning that I might be asked about it. But that’s literally all I have heard about it.”

She had never personally heard of matches being fixed. “Not that I’m aware of,” she said. “When I’m playing – and I can only answer for me – I play very hard, and every player I play seems to play hard. As an athlete, I do everything I can to be not only great, but historic. If that’s going on, I don’t know about it. I’m kind of sometimes in a little bit of a bubble.”