The former Germany captain has revealed that the Bavarians had accepted an offer from the Catalans for his services only for then general manager and current president Uli Hoeness to pull the plug on the deal after that summer's European Championship in Portugal.
"Yes, it's a shame that in 2004 I could not complete my transfer," Ballack confessed during an interview with Mundo Deportivo.
"We had reached an agreement with the club and we had the approval of Uli Hoeness but I was ultimately thwarted in signing that summer.
"After Euro 2004 Hoeness told me that I was not transferable and prevented my move.
"Of course, I was angry and disappointed that Bayern had given the OK to my departure to Barcelona, which was all agreed.
"Sometimes I think of what it would have been like to play with [Lionel] Messi, Xavi, [Andres] Iniesta and Barca's other stars.
"I was very excited about the idea of coming. In 2006 I ended up at Chelsea on a free transfer, so Bayern did not see a euro for me."
Ballack had been set to face Messi and his colleagues with current club Bayer Leverkusen on Tuesday night but the veteran midfielder has been ruled out of the Champions League clash with a muscular problem.
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