WBC heavyweight champion Deontay Wilder has threatened to retire if he is beaten by Bermane Stiverne on November 4.
Undefeated Wilder beat Stiverne in January 2015 to win the WBC belt - the only one of his 38 fights to go the distance - and has successfully defended his title five times since.
However, a proposed defence against Luis Ortiz at the Barclays Center in Brooklyn fell through when the former WBA champion failed a drug test.
It was followed by Anthony Joshua's Principality Stadium showdown against Kubrat Pulev being changed late on when the Bulgarian suffered a shoulder injury. IBO, WBA, IBF champion Joshua takes on Carlos Takam in Cardiff on Saturday.
The collision course Wilder and Joshua are seemingly on shapes as the heavyweight division's next blockbuster following the Brit's 11th-round knockout of Wladimir Klitschko in April, but American Wilder warns he may not get that far if Stiverne proves too much to overcome.
"If Bermane Stiverne beats me, I will retire," a passionate Wilder said during a media conference call. "I will be out of the way. Boxing ain't got to worry about me because it ain't doing me any good anyway. Nobody wants to fight. All I want to do is prove that I am the best and the best don't want to fight, so what's the point?
"If Bermane beats me, y'all won't have to hear about me no more. I'm done. It don't get more serious than that, so let the games begin.
"I may move to MMA or some s***."
Wilder continued: "It starts to sicken me and I don't want to feel this way about boxing because I was once in love with it. It makes me rethink my career. Am I better out of this sport than in it because of the stuff that's going on?
"Am I that dangerous to other fighters they fear they have to do certain things when it comes to Deontay Wilder?
"All I ever wanted to do is fight the best. It just saddens me with some of the activity going on in this sport."