Los Angeles - Oscar de la Hoya's boxing promotion company is suing Floyd Mayweather's manager and investors for $300 million, alleging they're trying to illegally monopolise US championship fighting.
Golden Boy Promotions filed the federal antitrust and unfair competition suit on Wednesday in Los Angeles.
It names Al Haymon, his companies, and the venture capital firm Waddell & Reed Financial.
The suit alleges Haymon, who represents more than 150 fighters, violates the federal Muhammad Ali Boxing Reform Act and also California and Nevada state laws by acting as both manager and promoter.
While Haymon doesn't call himself a promoter, the suit claims he has forbidden his boxers to sign with other promoters and both arranged and paid for sponsors, arenas, and TV air time for championship matches - and even paid the purses.
Messages left at Waddell & Reed and Haymon's Premier Boxing Champions weren't immediately returned.