The possible rematch comes after Alvarez was suspended for failed drug tests.
Gennady "GGG" Golovkin is uncertain if he will get a rematch against Saul "Canelo" Alvarez in September, according to ESPN.
Alvarez will return from his six-month suspension on August 17, which would make him eligible to fight GGG in September. He was suspended in mid-April for testing positive twice for the banned substance clenbuterol.
However, Golovkin questions if the September fight will happen because Alvarez is not currently in a drug testing program.
"There is a question mark about whether there will be a fight in September or not," Golovkin told ESPN. "I have nothing to hide, but I don't see any willingness from the other side to offer some fair conditions. Maybe they will do better, but at this point, no."
Golden Boy Promotions head Oscar De La Hoya has insisted that Alvarez enroll in a drug testing program ahead of a rematch.
Under his Nevada suspension, Alvarez does not have to take any drug tests until a month before his next fight. But Golovkin thinks Alvarez should be tested during his suspension.
"He's not being tested, and that tells a lot," Golovkin said. "I'm clean. I don't have any problems. I feel comfortable answering those questions. They keep saying things like nothing happened."
The possible fight between Golovkin and Alvarez would be a rematch from a fight last September that ended with a controversial draw. Judge Adalaide Byrd scored the fight 118-110 Alvarez over GGG, who many thought was the winner.
The rematch was originally schedule for May 5 but got canceled in early April after Alvarez tested positive.
Golovkin will defend two of his three middleweight championships on Saturday against Vanes Martirosyan, who stepped up to take Alvarez's spot after he was disqualified.