British billionaire Jim Ratcliffe's Ineos company officially joined the race to buy Manchester United on Tuesday.
United's owners, the Glazer family, said they were willing to listen to offers for the Premier League club in November and Ratcliffe is keen to strike a deal.
Boyhood United fan Ratcliffe, who made an unsuccessful £4.25 billion ($5.2 billion) bid to buy Chelsea last year, has long been linked with the Old Trafford outfit.
"I can confirm that we have formally put ourselves into the process," an Ineos spokesman told AFP.
After failing with his Chelsea takeover when Roman Abramovich sold the Blues to American tycoon Todd Boehly and his consortium, Ratcliffe is back in the hunt for a Premier League giant.
United have yet to comment on the news of the 70-year-old's interest in taking over from the United States-based Glazers.
But, born in Failsworth, Greater Manchester, Ratcliffe is one of Britain's richest men and might be more palatable to the United support than the Glazers, who have experienced numerous fan protests during their troubled reign.
The Glazers, who completed a leveraged takeover of the club in 2005, have proved deeply unpopular with supporters due to the team's declining fortunes on the pitch in recent years.
Their purchase of United also saddled the club with huge debts and they have long been accused of taking more out financially than they have invested in terms of transfer funds.
The Glazers further angered United fans by backing the failed European Super League project in April 2021 which would have led to the club joining a breakaway competition.
A statement from United in November said the board will "consider all strategic alternatives, including new investment into the club, a sale, or other transactions involving the company".
United have not won the Premier League since 2013 and their last major trophy came six years ago.
After a dismal sixth-place finish in the Premier League last season, United have been revitalised by boss Erik ten Hag and sit fourth in the table after beating arch rivals Manchester City 2-1 on Saturday.
- 'One of the biggest sports brands' -
Ineos is keen to expand a sporting portfolio which already includes ownership of French side Nice and Swiss team FC Lausanne-Sport, as well as the cycling team Ineos Grenadiers, formerly Team Sky.
Ratcliffe may face competition from Saudi Arabian investors after the country's sports minister Prince Abdulaziz bin Turki Al-Faisal said in November there "could" be interest in buying United and Liverpool, who are also up for sale.
American investment firm Raine Group, who handled Chelsea's sale, are exclusively advising United, who are valued at around £5 billion.
Ratcliffe's entry into the bidding process came just hours after United legend Peter Schmeichel defended the club's decision to set up a luxury lounge at the World Economic Forum in Davos.
Positioned near global software companies, consultancies and banks, the club has created a lounge on the main high street of Davos, a luxury Swiss ski resort teeming with billionaires and CEOs this week during the annual Forum.
"If you look at what we say about ourselves -- we say that we are one of the biggest sporting brands in the world -- then I think you have to back it up by having a presence in places like this," Schmeichel, who is acting as an ambassador, told AFP.
Schmeichel, who won five Premier League titles and the Champions League with United, said his personal preference would be for fans to buy the club, but he conceded that this was an unlikely outcome.
"I know there's a lot of fans who are wanting a change in ownership," he said.
"For me... would it make a difference to change the ownership? I think the only difference would be if it was owned by the fans, but I think that's probably impossible. It's too big."