Manchester United's attempts to attract Ronaldinho to Old Trafford collapsed on Saturday when the Brazilian joined Barcelona for £21m.
Barca reached an agreement with Paris St Germain to sign the midfielder on a five-year contract.
And the 23-year-old passed his medical on Sunday, with medical chief Jordi Ardevol describing the player as being in "excellent shape".
United's bid to sign the player failed even though they offered France goalkeeper Fabien Barthez to PSG as part of their original offer.
Barthez, who joined United three years ago for £7.8m from Monaco, was dropped by manager Sir Alex Ferguson towards the end of last season, prompting the recent purchase of United States keeper Tim Howard.
Earlier, United had set a deadline for PSG to agree or reject their final offer which was made on Friday.
But the long-running saga took a dramatic twist when Barcelona announced they were close to signing the Brazilian star.
Barcelona spokesman Juanho Castillo said on Saturday: "We are finally in agreement.
"In many ways I think the player would prefer to come to Barcelona for the weather and other factors. It's closer in culture to the Brazilian way of life.
"We have been very careful in our dealings with Barcelona to make every step in the process with a lot of sensitivity."
Manchester United boss Sir Alex Ferguson had wanted to sign Ronaldinho before jetting off on the club's pre-season tour of America on Saturday.
He visited Paris on Thursday in an attempt to seal the deal, but PSG president Francis
Graille was unimpressed by United's tactics.
"Manchester United have been too sure of themselves, believing that they'd done the hard work by negotiating directly with the player and going behind PSG's backs," he said.
"Despite Alex Ferguson coming as a guest star they never wanted to confirm their verbal offer of £21m.
"Manchester started their negotiations at a very low level on the financial front, including Barthez in their initial proposition. Their offers were always inferior to Barcelona's."
It is now possible that United could turn their attentions to trying to hi-jack Chelsea's bid to sign Damien Duff from Blackburn Rovers.
Chelsea had a £17m bid accepted for the Republic of Ireland international, but the player has still to agree personal terms with the London club.