Anthony Joshua's promoter Eddie Hearn is "very confident" the Deontay Wilder fight will be agreed after starting talks with the American's team.
A blockbuster bout between Joshua and Wilder for all the world heavyweight titles could be staged this year as the Matchroom Boxing boss has contacted Wilder's camp to begin negotiations, which also include the American TV network Showtime.
Joshua has called for a fight with WBC king Wilder as he bids to become the undisputed champion, after adding the WBO belt to his WBA 'super' and IBF titles following Saturday's points win over Joseph Parker.
But Hearn has again warned of how this fight needs to be staged in 2018 as Joshua could soon find it hard to retain all of his belts due to the different title commitments of the various governing bodies.
"I saw Deontay Wilder's Instagram post and it's very confusing," Hearn told Sky Sports. "Whoever is supposed to be calling or emailing me needs to update their contacts because once again it was us initiating the conversation.
"I called Al Haymon's team yesterday and spoke with Showtime last night and discussions are ongoing.
"I have a meeting with Anthony [Joshua] and Trainer Rob [McCracken] tomorrow where we will map out the rest of 2018.
"I will say it once again, the window for fighting Wilder is 2018, otherwise we will risk it not being an undisputed fight.
"Anthony wants the fight and I'm very confident it will happen."
Wilder said earlier this week: "I accept that challenge and I am ready to come to the UK for my next fight. There is nothing on Team Wilder's side to prevent me from fighting you next."