Newcastle United owner Mike Ashley has told Barry Moat to stump up the £80million asking price if he is serious about buying the Magpies.
The north-east businessman has been involved in protracted talks with Ashley since the summer, but the current Magpies owner has warned Moat that his patience is beginning to wear thin.
Ashley has twice put the club on the market - the second time following their relegation from the Premier League at the end of last season.
"Barry Moat has been driving me mad for two years," he told The Times.
"If he wants to buy the club, he's got a one-off opportunity to come up with the cash - £80million up front.
"I have to put £20million a year into the club - I spend more than every other fan put together puts into the club each year.
"If you can't pay up front to buy the club, you can't afford it."
Meanwhile, Ashley has admitted he regrets his decision to become involved with the St James' Park club two years ago.
He added. "Of course I regret it. I never said I was an expert in football clubs.
"I tried my best. But I accept my best was woefully short."