Sky Sports sources understands a fourth offer has been made for Rangers and that administrators are awaiting details from a fifth bidder.
Rangers administrator Paul Clark revealed last week that three bids had been submitted for the troubled Scottish giants.
Sale Sharks owner Brian Kennedy and a consortium led by former Rangers director Paul Murray both confirmed they had lodged takeover proposals on last Friday's deadline set by administrators Duff and Phelps.
Groups from America, the Middle East and Far East have been linked with moves for the Ibrox outfit and now a fourth mystery bid is thought to be on the table for the club.
An offer from a fifth bidder is also believed to be under consideration from Duff and Phelps as they weigh up the best deal to take Rangers forward.
Duff and Phelps admitted last week the offers were only indicative or conditional as all parties were looking for more clarity on complex issues.
These include the club's undetermined tax dispute, a legal case with investment firm Ticketus over a season ticket deal, which resumes on Wednesday in the Court of Session in Edinburgh, and the status of majority shareholder Craig Whyte
Rangers went into administration last month after HMRC lodged its petition over non-payment of around £9m in PAYE and VAT with the club also facing six disciplinary charges from the Scottish Football Association and a Scottish Premier League inquiry into alleged undisclosed payments to players before Whyte took over.