Ronaldinho was heavily linked with a move from France to Old Trafford in 2003 but ultimately landed in Barcelona to the tune of £21 million.
The two-time FIFA world player of the year then led the Catalan club to successive Primera titles and the 2006 Champions League trophy with a 2-1 victory over United's Premier League rivals Arsenal.
And the 32-year-old didn't leave United officials wondering 'what may have been' had he moved across the channel instead of heading south to Spain.
"If Manchester United had signed me, they would have won more European Cups," Ronaldinho told sambafoot.com.
"I have played for some of the biggest teams in the world and won everything."
After five years with Barcelona, Ronaldinho moved to AC Milan – despite reported interest from Manchester City – before returning to his native homeland with Flamengo.
But despite never playing in the Premier League, Ronaldinho said when he looked back on his European careers, there was only one nagging thought which left him troubled.
"The only regret is not playing more seasons with Lionel Messi," he said.