Andy Roddick is suing a charity but has pledged to donate any fee he receives to charity.
Roddick, who retired from tennis last year, claims he is owed $100,000 (£66,000) Miracle Match Foundation after playing in an exhibition match.
The Michigan-based foundation, which raises money for leukaemia sufferers, however has a history of raising paltry amounts. And after the cheque for Roddick supposedly bounced, he is taking the legal route.
"I simply expect Miracle Match Foundation to live up to their word and obligations," Roddick told Tennis.com
"They have repeatedly had issues paying the participants of their matches and very little of the money raised from these events actually goes to charity."
He added: "One hundred per cent of the money I win in this case will go to the charities, which were originally supposed to benefit from that night."
Thirty-year-old Roddick, the 2003 US Open champion, reached the Wimbledon final on three occasions but was beaten by Roger Federer each time.
He retired after last year's Grand Slam at Flushing Meadows.