Malcolm Glazer, the US sports tycoon stalking Manchester United, has appointed NM Rothschild to advise him on a bid for the football club.
Rothschild is working on a proposal it hopes will be more attractive to the United board than previous attempts by Mr Glazer to buy the club.
To win the support of the club's fans and its board, Mr Glazer is preparing to set aside substantial funds for investment in players and the expansion of the club's Old Trafford stadium.
Mr Glazer's most recent attempt to gain control of the club ended in failure last year with the resignation of JPMorgan, the bank that was providing most of the money for a £700m-plus bid.
The United board had been critical of Mr Glazer's bid plans, saying his proposals would saddle the club with too much debt.
On Friday the club said: "We don't intend to reopen discussions on this matter until we receive a definitive proposal from Glazer."
The United board has become weary of Mr Glazer's exploits. At the club's annual meeting Mr Glazer succeeded in voting three United directors off the board, including Maurice Watkins and Andy Anson, United's commercial director.
The club is exploring ways of shoring up its shareholding structure to ensure the company can repel any unwanted attention.
But shoring up the shareholder base could be difficult because almost 60 per cent of Manchester United is owned by two investor groups.
JP McManus and John Magnier, the Irish horse racing magnates, own more than 29 per cent through their Cubic Expression vehicle, while Mr Glazer and his family hold about 28 per cent.
Rothschild almost took a mandate from the Glazers last summer. The bank is believed to have begun discussions with the family at the end of last year when it started looking for new advisers.
Rothschild declined to comment.
However, it is believed to be working for Mr Glazer and his family in an advisory capacity only and is not expected to provide debt finance for any bid.
Mr Glazer's interest in the club is being led by his two sons, Joel and Avi.
The pair are both fans of English football and want to bring the expertise they have learnt running the Tampa Bay Buccaneers American football franchise to the UK.
Mr Glazer could not be reached for comment.