He had been due to fight Avtandil Khurtsidze
Billy Joe Saunders' world title defence next month's been cancelled after his opponent was arrested in New York.
Avtandil Khurtsidze was taken into custody for alleged links to organised crime.
The Georgian was due to fight Saunders for the WBO middleweight belt in London, but has been told he cannot leave the US.
Promoter Frank Warren said: "Obviously we are all very disappointed and frustrated but this is a situation that is completely out of our hands. I’m currently speaking with the WBO to see what the next step is for Bill.
"The WBO have ordered that Billy must have a Mandatory defence next. At the moment, that is could still be against Khurtsidze but we will not know for sure until the WBO give their ruling. Unfortunately, it isn’t as simple as going out and finding someone to step in for Khurtsidze.
"We should have some news next week and it’s a case then of regrouping and doing what is best for Billy’s career. He and I want the winner of Canelo v Golovkin after his Mandatory. That’s still the plan and I will do everything I can to make that happen."
The fight had been scheduled for July 8th at the Copper Box Arena in London.
Saunders won the WBO Middleweight world title after beating then champion Andy Lee of Ireland at Manchester Arena in December 2015 before successfully defending his belt against Artur Akavov of Russia a year later.