Ineos owner Sir Jim Ratcliffe and Qatari banker Sheikh Jassim will submit improved bids to buy Manchester United after the initial deadline was extended at their request amid confusion on Wednesday night.
Bidders were told they had until 21:00 GMT to submit second, revised bids.
BBC Sport has been told several other proposed investors met the initial deadline.
It is unclear when the new deadline will be.
Ratcliffe and Sheikh Jassim are the only publicly declared bidders.
Initially on Wednesday evening there had been strong indications that the pair had submitted fresh bids.
It is now understood that over the past 24 hours both parties submitted requests to Raine - the investment bank conducting the sale - for more time to make their second offers, which was granted.
The situation is described as "live and fast moving" by someone close to the talks but it is thought both Sheikh Jassim and Ineos are committed to making second bids.
However the bizarre twist in the sale process will only reinforce concerns among some fans that American owners the Glazer family may decide not to sell the club.
Ineos wants to buy the combined Glazer shareholding of about 69%, but the Qataris are targeting 100% of the club.
Both sides met with United officials earlier in March.
BBC Sport has learned that United officials met eight different potential investors over a 10-day period of high-level meetings recently, including Ratcliffe and representatives of Sheikh Jassim.
The size of their initial bids has not been disclosed - with reports both are in the region of £4.5bn - but they were clearly far below the £5-6bn valuation that the Glazers have established, a figure that would smash the record £3.71bn paid for a sports team.
Whether they - or any other prospective bidders - are able to submit an offer that persuades the Glazers to sell is the next key question.
If not, and with United's fortunes improving significantly in recent months under manager Erik ten Hag, the Americans may well yet decide to retain the club and perhaps instead look to sell a minority stake to the likes of US hedge fund Elliott Investment Management.
The Glazer family said in November they were considering selling United.
Announcing its initial bid Sheikh Jassim's Qatari consortium said the offer "plans to return the club to its former glories".
Described as a life-long Manchester United fan, Sheikh Jassim is chairman of Qatari bank QIB and the son of a former prime minister of Qatar.
The Ineos group, owned by 70-year-old British billionaire Ratcliffe, has a history of investment in sport and owns French Ligue 1 club Nice and Swiss club Lausanne.
Its sporting portfolio also includes high-profile sailing team Ineos Britannia - led by Sir Ben Ainslie - and a five-year partnership with Formula 1 team Mercedes, while it took over the British-based Team Sky in cycling in 2019.
At the time of the first bid it was understood its proposal would emphasise Manchester-born Ratcliffe would be "a British custodian for the club" and would aim to "put the Manchester back into Manchester United".
