WADA director general David Howman tells the Associated Press he sent a letter to the ATP on Monday but he would not elaborate on what he said. He says he wants to protect "clean athletes" and "make sure that these sorts of things don't recur."

Agassi wrote in his soon-to-be-released autobiography Open that he ingested crystal meth and then lied to the governing body of men's tennis to avoid a suspension after failing a doping test.