But Ferguson's doubts were completely brushed aside as United hammered Schalke 4-1 at Old Trafford to win 6-1 on aggregate and book their spot in the May 28 final at Wembley Stadium where they will meet Barcelona.
"They did me proud," he told ITV1. "It was a semi-final and the fact it's such an important game does create a bit of doubt in your mind of 'Am I doing the right thing?' but I'm glad we were vindicated.
"It's fantastic for the club. We're where we want to be. I've said many times we should have done better in Europe over the years and I think this team can win the cup."
Ferguson made the changes with Sunday's Premier League blockbuster against Chelsea in mind. He wanted to ensure some of his stars were given time to get themselves 100% before they host the second-placed Blues who sit just three points behind them on the league table.