Anthony Joshua could respond to Deontay Wilder with a “counterproposal” as negotiations continue, his promoter Eddie Hearn said.
A $50 million offer from Wilder last week brought the undisputed heavyweight championship fight "closer", according to Hearn, despite a Thursday deadline expiring.
I will go back with some very simple questions, which hopefully they can answer, to put us in a position to know whether it is worth talking.
"We can't agree a deal until we have a dozen very important questions answered," Hearn told Sky Sports News on Monday.
"I'm thinking about making a counterproposal this week.
"I will go back with some very simple questions, which hopefully they can answer, to put us in a position to know whether it is worth talking.
"I have spoken to AJ multiple times - he wants this fight. Wilder wants this fight.
"I work for Joshua, he is my boss! If he tells me to make a fight, it is my job to make the fight.
"The gamble from their side is that they want Joshua in their backyard, in America, they want to beat him, and become undisputed champion.
"Okay, but we need a fair playing field. We need to make sure we have some control and input into this process.
"One of the questions - where is the fight going to be? We don't think that's obscene to ask.
"If it's in the UK the offer becomes more attractive. If it's in America, we can still do that, but we need to talk about these things."
Negotiations were ramped up when Joshua replied to Wilder's Instagram post last week saying "let's roll" - before the American's representative Shelly Finkel dished out a 48-hour deadline to their $50 million offer.
"They made an offer which we are interested in," Hearn explained. "I went back and asked for the terms of the contract, which was denied.
"We had a meeting last Friday which was cancelled. They didn't want to have a meeting because it was non-productive."
Joshua would bring the IBF, WBA and WBO titles into a potential fight against WBC holder Wilder.
Mandatory challenger Alexander Povetkin, Jarrell Miller and Dillian Whyte remain options for Joshua if his preferred fight against Wilder cannot be agreed.
Wilder could defend his title against Dominic Breazeale next, Hearn has previously claimed.