Secret files exposing evidence of widespread suspected match fixing at the top level of world tennis can be revealed by the BBC and BuzzFeed News.
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, including at Wimbledon.
All of the players, including several Grand Slam doubles winners, were allowed to continue competing.
The TIU told the BBC is takes dealing with corruption in tennis extremely seriously.
In 2011, Daniel Koellerer was banned for life from professional tennis over alleged match-fixing but denied the claims.
However, he told the BBC that on three occasions he had been offered large sums of money to deliberately lose tennis matches but refused to take part.