The Catalan side beat United 2-0 on that occasion, with many onlookers mesmerised by the way the Spanish side passed the ball and kept possession.
The victory handed Barcelona a third European Cup and completed a historic club treble. And yet Guardiola says a performance like that won't be enough to win at Wembley.
"We need to play much better than in 2009," he said. "We played worse in Rome than we wanted to. We want to play quicker than we did then.
"In 2009, in terms of our intensity during different stages of the match, there are a few things that weren't as good as they could have been. We won't be playing the same way we did two years ago."
Barcelona enter tonight's game as heavy favourites, with most neutrals predicting Catalan success. Guardiola isn't quite so presumptuous, admitting Sir Alex Ferguson's United side is more than capable of causing an upset.
"Manchester United worries me. From van der Sar, the goalkeeper... they have fantastic players. They're powerful, one of the most complete teams I've seen in all senses.
"Fergsuon said there were four or five different teams he could play, so that shows how much talent is in that team.
"Strong points? They've got a lot of them. Weak points? They've got a lot of them too."
Barcelona, famed for their beautiful football, had to resort to more attritional values in their high-profile semi-final tie against Real Madrid. The first leg, especially, was less a football match