Ronaldinho's advisers believe that the time is right for him to quit Spain and move to the Premier League.
But long-term fan Roman Abramovich's hopes of landing him could be scuppered - with sources close to the player insisting United, not Chelsea, is his preferred destination.
Fergie is convinced Ronaldinho can recapture the form which established him as one of the world's top stars - and would love him to do it at Old Trafford.
Despite his recent problems, Ronaldinho would still command an annual salary of around £7m, but the deal would still make commercial sense for United.
Nike, who are United and Barca's kit sponsors, will also be keen to keep the player at one of their clubs.
He thought a deal had been struck and later blamed Peter Kenyon, the Chelsea-bound chief executive, for failing to clinch the transfer.