Ace tennis player Novak Djokovic is on the verge of signing a contract with IMG after dropping previous marketing agents CAA Sports. According to the sources,IMG has negotiated huge endorsement deals for fellow players Rafael Nadal and Roger Federer. It is understood,billionaire Ron Burkle is also independently advising Djokovic,but a well placed source claimed the discussion between them is just on a friendly basis. Ron advises him on a friendly basis,while the situation on representation is between CAA and IMG, the New York Post quoted a well-placed source,as saying. Djokovic had recently said: I have had a contract with [CAA I think for four years. I tried to work it out,and it was successful,but I think I needed to move on.