The opponent for Nathan Cleverly's WBO world light-heavyweight title defence in Los Angeles on November 10 is expected to be named in the next 24 hours.
Unbeaten American Ryan Coyne withdrew from the contest after it became apparent his legal battle with his promoter Don King would not be concluded in time.
The pair were set to go to court on Thursday with King threatening Coyne and Frank Warren with a lawsuit, but now a new opponent will be sought.
Warren has drawn up a short list of three possibilities, although they would have to be ranked inside the WBO's top 15 in order for it to remain a title fight.
"Much as I hate to say it, this fight will not be going forward with myself involved in it," Coyne told BBC Wales.
"This is the biggest disappointment of my career.
"I trained very, very diligently for this fight and I was devastated when I got the news.
"I want to apologise to the fans in the United Kingdom and the United States that this fight won't be going ahead, but hopefully we can get it on at a later date.
"We just have to let the managers and attorney's sort this out."
Coyne's withdrawal is hugely disappointing for Cleverly, who opted for the LA date instead of a bout with Ukrainian Vyacheslav Uzelkov in Cardiff on October 27.