Talks on the potential £340m takeover of Newcastle United by Saudi Arabia's sovereign wealth fund are "advanced".
Negotiations between the Arab state's Public Investment Fund (PIF) and Newcastle owner Mike Ashley have been in progress for several months.
The chances of an agreement are now "high" according to one source familiar with the discussions.
But they also warned that the talks were "complicated" and a deal could still collapse.
"Ashley does not need to sell, and he is unpredictable," said the source.
Businesswoman and financier Amanda Staveley is understood to have approached the Saudi Crown Prince Mohammed bin Salman about buying the Premier League club.
Staveley failed to purchase the club two years ago after Ashley said he wanted to bring 10 years of ownership to an end.
She is thought to want a 10% stake in the club if a deal can be agreed with PIF, which would be the majority partner.
The Bin Zayed Group, representing UAE billionaire Sheikh Khaled bin Zayed Al Nahyan, was thought to have agreed terms for a takeover at Newcastle last year but it failed to materialise.
The takeover would be Saudi Arabia's latest venture into sports investment.
Rival Premier League club Sheffield United are owned by Saudi Prince Abdullah bin Mosaad bin Abdulaziz Al Saud, who took full control from Kevin McCabe last year.
Businessman Turki al-Sheikh, the chairman of Saudi's General Entertainment Authority, has also bought Almeria in Spain's second division.
Any deal for Newcastle would require approval by the Premier League, and would inevitability be controversial.
Global sports organisations have been accused of being complicit in what is seen as the country's attempt to 'sportswash' its human rights record. Football authorities have also become infuriated with a Saudi website's illegal piracy of Qatari-based sports TV coverage.
Human rights organisation Amnesty International says Saudi Arabia has "an appalling record on LGBT rights, women's rights, extra-judicial killings, beheadings, the murder of journalist Jamal Kashoggi, and their involvement in the ongoing conflict in Yemen".
Saudi Arabia has recently been making efforts to present itself as more liberal, and to open itself up to the wider world as a place to do business, watch sport and go on holiday.
Last year the country staged heavyweight boxing's rematch between Anthony Joshua and Andy Ruiz Jr and has just unveiled detailed plans for a new race track that is poised to host a Formula 1 grand prix from 2023.
Earlier this month the Spanish Super Cup was also staged there.
Felix Jakens, Amnesty International UK's Head of Campaigns, said: "Given the deluge of investment in sport we've seen from Saudi Arabia recently, a takeover of Newcastle United wouldn't come as a major surprise.
"It's not for us to say who should own Newcastle United, but players, back-room staff and fans alike ought to see this for what it is - sportswashing, plain and simple."
Staveley helped broker the purchase of Manchester City by Sheikh Mansour in 2008 and it was reported that she led Dubai International Capital's £400m bid for Liverpool in 2008.
Ashley, 55, has been a divisive figure at St James' Park, with some supporters regularly protesting about the way the businessman has run the club.
He bought Newcastle for £134.4m in 2007.
The club have been relegated twice from the Premier League during Ashley's 10-year reign.
Newcastle United, Staveley, and PIF have all declined to comment.