It was a resounding way for the European champions to respond to their Club World Cup final loss on Sunday but, according to Ivanovic, they were worried it would not turn out that way.
"Leeds was a very difficult game which came at a very difficult moment for us. We didn't have a lot of time to adapt," he said.
"We were tired and that is why it was a little scary for us at the beginning. We didn't know how we were going to feel at the start of the game, but now we have to look forward.
"We have to recover well because we still feel the strain from Japan and we will probably still be adapting a week after coming back."