Seventeen-time Grand Slam champion Roger Federer has said that he will only believe allegations of match fixing at the top level of tennis if those involved are named.
Earlier this week, BBC Sport claimed that 16 players, who have all been ranked in the top 50 at some point, had been brought to the attention of tennis authorities but not thoroughly investigated or punished.
Federer has said that the report needs to be taken very seriously but also wants more details revealed.
"I would love to hear names," PA quotes the Swiss as saying. "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."
World number one Novak Djokovic has said that he was once approached over a six-figure payment to throw a match, while Andy Murray admitted today that he would not be surprised if some matches were fixed.