They immediately began a spending spree, which quickly lifted them into contention for Champions League and Premier League title challenges.
But Ferguson, who until the takeover by Sheikh Mansour had led United to total dominance over Manchester football, was less than impressed with City’s new-found financial power.
Those comments have come back to haunt Ferguson, with City going on to become the dominant force in English football since the Scot retired.
And Carragher also believes that Ferguson will harbour regrets at playing down City’s chances of winning trophies despite their financial backing.
“Eleven years ago, Ferguson gave a fearless and provocative response to the claim his city rivals might dominate English and European football,” he wrote in a column for the Telegraph.
“‘They could buy every player in the world, but can they buy a team, can they buy a Manchester United spirit?’ he said of Manchester City’s emerging threat.
“‘The problem with having all that money is that you buy indiscriminately. Sunderland, in the 1950s, the Bank of England team – relegated. I wouldn’t wish relegation on City.’”
“It’s an understatement to say those comments – made at the start of the ‘noisy neighbours’ rivalry – have not aged well for the Old Trafford legend.”
If they go on to win the Carabao Cup and FA Cup, as well as confirm their Premier League title, City will have claimed nine of the last 12 domestic titles.
And Carragher believes that a look at City’s defeat of Borussia Dortmund in the Champions League quarter-finals is the only evidence Ferguson needs to prove that he was wrong.
“Over two games, they also enjoyed a touch of what United possessed in 1999, and we had in 2001. Luck at the right time,” he wrote.
“That’s a consequence of the trait Ferguson referenced in 2010 and something the Liverpool team of 2001 had in abundance – team spirit. You can’t put any price tag on that.
“Ferguson was right to say as much, but wrong when questioning whether City would ever possess that of his United side. He will have changed many of his opinions on the club since then.”