Eddie Hearn expects to finalise Anthony Joshua's world title defence against Kubrat Pulev in the wake of Wladimir Klitschko's retirement.
The Ukrainian's announcement on Thursday ended the prospect of a November rematch with Joshua, who won the pair's Wembley epic in April.
Pulev is next in line as the IBF's mandatory challenger, and Hearn has already started negotiations with the Bulgarian's promoter Kalle Sauerland.
Hearn told Sky Sports News: "When the IBF cleared the Klitschko rematch it was under the proviso that if it's not Klitschko it must be Pulev, so we've already got talks in place with Kalle Sauerland.
"Part of me is quite pleased we can move forward and draw a line under this. There was always the worry with Klitschko's age that we could announce the fight and he could get injured in camp, various bits and pieces like that.
"At Anthony's stage of his career, as young as he is, he's really raring to go already. He's been ticking over in the gym, he wants to start his camp and he's been calling me every day saying 'will he take the fight?'
"Now finally we've got an answer, so I think fight fans are going to see an announcement sooner than they would have seen with a Klitschko fight.
"A line's drawn, we can move on with our mandatory challenger and move towards more belts in the division."
Klitschko spoke in June of how his stock had risen despite defeat to Joshua, which came in the 11th round after both fighters had been floored.
Hearn said: "It's unusual to bow out on a loss where you've probably gained more respect for that loss than you have for your entire career.
"I think that's probably one of the driving factors that's made him say 'I'm going to bow out after an epic night.
"The way he acted in and out of the ring - he's a really nice man. Part of me, as much as I wanted to go to Las Vegas for this fight, is also pleased for Wladimir Klitschko that he can leave this sport with a very healthy bank account and, more importantly, with his health intact after a great career."