"The sending off made it difficult for us," added Ferguson.
"It's a soft sending off but he swung an elbow. When you do that in front of the referee you've got no chance. He gave the referee no option.
"Half an hour to go is a long road with 10 men but Wayne scored a magnificent goal.
"After Vidic was sent off it was important that we didn't lose the ball. It was important to keep passing and hope Ronaldo or Rooney did something special.
"In 30 years you'll look back and see Manchester United's name on the trophy, although I won't be around to enjoy it."
Rooney was named player of the tournament after the final - and was clearly delighted to have the scored the winner.
"We're the best team in the world," said Rooney, who also scored twice in the 5-3 semi-final victory over Japan's Gamba Osaka.
"It's a great achievement for the team and something we're all really proud of. It's been a long road.
"To score the winning goal in a match like this is a great feeling for me personally."
United return to Premier League action with a fixture against Stoke at the Britannia Stadium on Boxing Day.
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