Rangers administrators Duff and Phelps have instigated legal proceedings against owner Craig Whyte's former lawyers - a claim which is understood to be in the region of £25 million.
The move came as the administrators remain hopeful of announcing a preferred bidder for the club this week after holding talks with the two remaining interested parties on Tuesday.
Administrators hope a deal for the Glasgow giants can be concluded "without any further delay'', with manager Ally McCoist today calling for a quick resolution to the bidding process.
Former Ibrox director Paul Murray's Blue Knights consortium on Monday took a step back from the race to buy the club, leaving Bill Ng's Singapore consortium and American tycoon Bill Miller still in the running.
Paul Clark, joint administrator, said: "We would like to inform all Rangers supporters that today discussions have been held between members of the administration team and the two remaining bidders in the sale process.
"A number of issues have been examined and we have made it clear to all those involved in the bidding that it is of paramount interest to the football club that a satisfactory deal be concluded without any further delay.
"It is our intention to announce a preferred bidder this week and we can assure all supporters of the club that we are doing everything in our power to make that happen.
"We can also confirm that we have instigated legal proceedings against Collyer Bristow, the former lawyers of the club, and The Rangers FC Group Limited in the High Court in London for substantial damages suffered by Rangers Football Club.''
Last month, a High Court judge instructed that £3.6 million once held in the account of Collyer Bristow be transferred into the safekeeping of the administrators' lawyers, Taylor Wessing, with several parties claiming the money is theirs.
Parties with claims against Collyer Bristow were informed they should bring their claims by April 16.
Clark said at the time that Duff and Phelps had "substantially larger claims against Collyer Bristow'', which they wished to bring as soon as possible.
A spokesman for Collyer Bristow told www.thelawyer.com: "On March 23 Rangers administrators' made a request to vacate the previously agreed court date in order that they could consider bringing 'wider claims' against Collyer Bristow in relation to the takeover of Rangers Football Club and its subsequent administration.
"At this time the court set a deadline of April 16 for parties involved in the transaction to submit their claims. As expected, late yesterday evening Collyer Bristow received detailed particulars of the claim on behalf of the administrators' Duff & Phelps.
"A significant proportion of the damages claimed by the administrators (in excess of £25 million) relate to claims for 'consequential loss', which we believe to be highly speculative.
"As we have previously stated, it is our intention to contest all claims brought by the administrators in the strongest possible terms and this remains our position.''
Meanwhile, McCoist called for administrators to name a preferred bidder as soon as possible after expressing concerns over the protracted nature of the bidding process.
He told Blues News: "There obviously have been developments and it looks like the preferred bidder status has moved away from the Blue Knights and perhaps headed to either the American bid or the Singaporean bid.
"Obviously, like all Rangers fans, I think the sooner the preferred bidder status is announced would be a big, big step in the right direction. The uncertainty and the lack of clarity about the future is obviously really concerning and worrying for everyone, be that players, staff or fans.
"I can totally understand everybody's concern and that's why I'm hopeful that it will be sooner rather than later. I won't lie to you. I'm really concerned and really worried because we have a lot of planning to do.
"We have pre-season games and hopefully we'll try to arrange pre-season tours. All these things and players coming and going makes it concerning.''
The Blue Knights were set to be named preferred bidder on Friday but financial backers Ticketus would not pay the non-refundable deposit, reported to be £500,000.
The group raised the cash themselves but, amid the delay, discovered Ng had made what Murray called a "substantially'' better offer to Ticketus.
Murray added that they were not able to match Ng's offer and were stepping back from the process in a bid to help Duff and Phelps agree a deal with the Singapore group and avoid liquidation.
However, Ticketus - whose contract with the club gives them the right to £27million of season tickets over the next three years - remain happy to work with Murray.
A spokesman for Ticketus said: "Discussions with both bids are ongoing and ultimately we are prepared to work with whichever bid the administrators think is best for the club.''
It is understood Ticketus remain happy with the proposals on offer from the Blue Knights, which would see them recoup £10million of their money over a longer time period in return for helping to finance the deal.
The investment firm are also willing to work with Ng, who got in touch with the group because they are currently the biggest creditor, although Her Majesty's Revenue and Customs could be owed more should a tax tribunal go against Rangers.
Rather than be the deal-makers, Ticketus feel it is up to the administrators to decide who the preferred bidder is and they will react accordingly.
It is understood they have held no talks with the other interested party, US businessman Miller. Ng claims his consortium has not yet struck a deal with Ticketus. He told BBC Scotland: "We have not agreed on any terms with Ticketus at the moment.
"I do not want to speculate on the reasons of Blue Knights' withdrawal but the apparent withdrawal from the bidding process by the Blue Knights means only that the chances of taking over increases for the two remaining bidders left in the process.''
Sale Sharks owner Brian Kennedy has declared himself ready to re-enter the race should a deal that includes a CVA fall through.
Kennedy, who saw his indicative bid rejected last month, said today: "I do not want to distract the time-critical process of appointing preferred bidders.
"However, should this fall through with the effect of endangering the existence of RFC, I would reconsider my position.''