Anthony Joshua could be forced to turn to Kubrat Pulev after Deontay Wilder opted not to face his fellow world champion this year.
Wilder will instead rematch Luis Ortiz in the autumn in a repeat of their clash last year which saw Wilder wobbled before prevailing in the 10th round.
Should Joshua beat Andy Ruiz Jr in New York on Saturday he will require an opponent for later in the year.
And Pulev, who was due to challenge the Brit in 2017 before suffering an injury, will be near the top of the queue.
The Bulgarian will eventually be called as Joshua's mandatory challenger having beaten Hughie Fury last year.
Alternatively, Joshua could agree to a rematch of his own with old rival Dillian Whyte.
Whyte rejected a career-high pay day to face Joshua on April 13 at Wembley and will instead take on the dangerous Oscar Rivas in July.
He could then challenge Joshua at Cardiff's Millennium Stadium in the autumn.
Wilder said on Thursday: "To all my fans, I want to announce that Luis Ortiz and I have signed for a rematch, with the date and site to be announced shortly. All my controversial fights must get dealt with ASAP."
The announcement also implies Joshua may have to wait in line behind Tyson Fury following his controversial draw with Wilder last December.
Fury was dropped twice in Los Angeles but recovered to hear the final bell only to be denied victory by the ringside judges.
He then pulled out of the rematch negotiations after signing a five-fight, £80million deal with US broadcaster ESPN and will instead fight unknown Tom Schwarz on June 15.
Fury is also highly unlikely to agree to face Joshua this year.
