The Glazer family confirmed they had no interest in doing a deal to offload the Old Trafford outfit, even if the offer price shoots beyond £1billion.
Their statement seemed to end any hope of the Red Knights consortium taking control, even though they are intent on making a bid for United and trying to reduce the huge debts incurred by the Glazer family takeover in 2005.
However, the Manchester United Supporters Trust, who launched the green and gold campaign at the start of the year, are refusing to buckle, insisting they will carry on their fight.
"The last time Manchester United was 'Not For Sale' was back in 2005 and what happened next - the Glazer family bought it," said MUST chairman Duncan Drasdo.
"It is clear from the reactions on the Manchester United message boards that supporters are not buying into the spin coming out through the Glazers' PR machine.
"If the club really isn't for sale why would they need to say anything at all? Why are they so concerned about telling everyone they don't want to sell? If they don't want to sell they can simply reject any offer. It sounds like the gentleman doth protest too much."
Should a Red Knights bid be turned down, as now appears certain, MUST are expected to call for a boycott of season tickets and other merchandise in an effort to hit the Glazers' various income streams.
Yet United have appeared increasingly bullish about the effect such a call would have, with chief executive David Gill recently claiming the sale of season tickets was virtually in line with expectations and not giving any hint of a potential problem.
Certainly there appears little that is going to shake the Glazers from their position, having reported a reduction in the overall debt to £520million and growth in all areas, with the exception of a relatively minor £1million decline in matchday income.
"The board noted recent press speculation regarding a possible bid for Manchester United," the statement read.
"The owners remain fully committed to their long-term ownership of the club.
"Manchester United is not for sale and the owners will not entertain any offers."