Michael Avenatti’s biggest case yet: His own

The way Mr. Avenatti approached Nike reflected seemingly little research, according to people who closely follow the company. Nike has ridden out scandal before, including in the Justice Department’s prosecution of international soccer officials for bribery and corruption in the FIFA case, in which Nike was implicated but not charged.

It is unclear if Mr. Avenatti possessed evidence directly tying Nike to any payments, and prosecutors and Nike both declined to comment.

“Avenatti was an idiot to think that he was going to make a company like Nike buckle,” said John Horan, the longtime publisher of Sporting Goods Intelligence, an industry newsletter.

Mr. Avenatti insisted that he simply wanted to clean up what he called corruption within Nike and conduct an internal inquiry to ensure things improved. “This was a complete hit job by Nike. It was designed to do damage to me and inoculate themselves,” he said by phone from California.