I remember that was the problem in making the second Canelo vs Golovkin fight, but Golden Boy made an offer to Golovkin for the September 2019 fight which Golovkin rejected. As reported by Idec on this site on June 20:
"Sports Illustrated’s Chris Mannix reported Thursday morning that negotiations for their third fight have stalled largely due to Golovkin’s reluctance to face Alvarez in Las Vegas for a third time. The former middleweight champion made it clear in the aftermath of his fourth-round knockout of Steve Rolls on June 8 that he wants their third fight to take place elsewhere.
According to Mannix, also a commentator for DAZN, promoter Oscar De La Hoya will start looking at other opponents for Alvarez’s next fight if they can’t come to a resolution by Friday. Mexico’s Alvarez, the IBF/WBA/WBC middleweight champion, is scheduled to return to the ring September 14."
"Sports Illustrated’s Chris Mannix reported Thursday morning that negotiations for their third fight have stalled largely due to Golovkin’s reluctance to face Alvarez in Las Vegas for a third time. The former middleweight champion made it clear in the aftermath of his fourth-round knockout of Steve Rolls on June 8 that he wants their third fight to take place elsewhere.
According to Mannix, also a commentator for DAZN, promoter Oscar De La Hoya will start looking at other opponents for Alvarez’s next fight if they can’t come to a resolution by Friday. Mexico’s Alvarez, the IBF/WBA/WBC middleweight champion, is scheduled to return to the ring September 14."
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