R&B star R. Kelly's former manager is suing the singer for cash he insists he's owed.

Derrel MCDavid claims he has been the man behind the I Believe I Can Fly hitmaker for decades, and had hoped to keep cashing on in his client's success after they parted ways last year (13).

According to his lawsuit, obtained by Tmz.com, Kelly agreed to hand over $1.3 million (Gbp760,000) as a parting gesture but the manager has seen nothing since an initial $300,000 (Gbp176,000) payment.

He claims Kelly agreed to pay him $40,000 (Gbp23,500)-a-month for 18 months, and he is suing the singer for the full balance of what he claims he is owed.