The YouTuber Paul will now face MMA fighter Tyron Woodley, who has been drafted in as a last-minute replacement. Paul has already beaten Woodley in Cleveland in August, where he won an eight-round bout by split decision.
After the fight in Cleveland, Paul and Fury, who was fighting on the same card, had a heated verbal exchange and have continued to bait each other in the following months. All helping stoke the fire under the December fight's PR machine.
Fury, the brother of heavyweight world champion Tyson Fury, has missed training in recent days and has now withdrawn from the clash.
Fury claimed he is suffering with a bacterial chest infection and a broken rib, but he showed no signs of either during a press conference last week.
"I am absolutely heartbroken that I have been forced to withdraw from my fight with Jake Paul due to a bacterial chest infection and broken rib," Fury said.
"The beginning of my camp was going so incredibly and I never expected anything to come in my way from a victory on December 18.
"I can't express now disappointed I am and I really do hope we can get this fight rescheduled in the new year. I want this fight to happen more than anything. I'm now regretfully putting my focus on recovery and a further reschedule date."
Paul has responded to Fury's withdrawal through social media in true style, and also threw in a $500,000 bonus to Woodley if his new opponent knocks him out.
Paul took to Twitter on Monday afternoon: "It's official, Tommy Fury is boxing's biggest b****.
"The Furys have pulled out of the fight due to a 'medical condition', who knows what the f*** is going on in that camp.
"I couldn't believe the news at first, it still doesn't even seem real. He fumbled the biggest bag of his life - now he will be paying me 60 dollars [to watch] instead of getting paid millions of dollars to fight me.
"I've fought with a broken nose, I've fought sick. Get the f*** over it, this is boxing. I think the pressure got to him."