Boris Becker is believed to have borrowed £2 million from a British telecoms billionaire amid claims he may sell his Wimbledon trophies to help pay off an alleged £54 million debt.
The three-times Wimbledon champion was declared bankrupt in June.
Becker's costly divorce from his first wife, and a series of failed business ventures has seen his assets dwindle from £35 million to just €540,000, according to German magazine Stern.
The fall from grace led Becker to ask for a loan from John Caudwell, the co-founder of Phones 4U.
Mr Caudwell, whose daughter worked as a personal assistant in Becker's London office, agreed to loan him £2 million, with the interest rate set at 25 per cent.
A spokesman for Mr Caudwell told The Times the loan had been repaid, although later than agreed.
Becker's financial woes are said to have spiralled, with the six-time Grand Slam winner now owing £10.5 million to Arbuthnot Latham & Co, a private London bank.
He is also believed to owe €38.4 million to Hans-Dieter Cleven, his long-term business adviser.
It is understood that his total debts amount to more than £54.4 million, a figure "vehemently denied" by his lawyer, Christian-Oliver Moser.
Becker was said to be considering selling his Wimbledon trophies, which are kept at his £7 million London home.
His agent was unavailable when approached for comment on Thursday night.