Manchester United have granted extensions to British billionaire Jim Ratcliffe and Qatari banker Sheikh Jassim bin Hamad Al Thani to submit new bids for the 20-time English champions.
Both parties were expected to increase their initial offers after the submission deadline of 9pm GMT (1am UAE) was extended by merchant bank Raine, which is assisting with the sale of the club, following confusion over the timing, British media reported.
Neither Manchester United or Raine have given a new deadline for the increased offers.
It is believed United's owners, the Glazer family, value the club at £6 billion ($7.3 billion) which, should it be met, would be a world record for a sports club.
Although no details have been released of any bids, it is believed that Ratcliffe's and Sheikh Jassim's bids fell short of the Glazers' valuation.
Sheikh Jassim's bid for 100 per cent control of the club promises to wipe United's $620 million debt and invest in a new stadium and training ground, in addition to backing for the men's and women's teams.
A source close to Sheikh Jassim's bid told AFP he remains confident his bid is "the best for the club, fans and local community".
Ineos chief executive Ratcliffe, 70, said in a recent interview with the Wall Street Journal that he would not pay a "stupid" price in a bidding war for one of football's most famous clubs.
Ratcliffe's initial bid was to acquire the 69 percent stake owned by the Glazer family. The boyhood United fan said his interest in buying United would be "purely in winning things".
The Glazers have been massively unpopular with United fans since their leveraged £790 million takeover in 2005. There have been several large-scale protests against their ownership.
However, they could yet shun the option of selling a controlling stake in the club, with other parties interested in a minority shareholding.
Elliott Investment Management has also reportedly made it through to the second stage of the process, although the company is said to be offering funding rather than a takeover.
Bidders are expected to hear from United next week, with another round of bidding still in play.
If one bid is vastly ahead of the others, it could be chosen to enter into a period of exclusivity, which would allow further negotiation ahead of a final sale.
Ratcliffe visited Old Trafford last Friday along with Ineos representatives, a day after a delegation from Sheikh Jassim's group toured the club's stadium and training ground to hold more talks as part of their due diligence.
Ratcliffe made a last-minute bid to buy Chelsea last year after they were put on the market by Roman Abramovich, who was forced to sell the club due to his alleged ties to Russia President Vladimir Putin after the invasion of Ukraine.
An American consortium headed by Todd Boehly won the bid to take over the West London club, paying £2.5 billion, and vowing to commit £1.75 billion in further investment.