Both teams have displayed an admirable commitment to attacking football, and in Lionel Messi and Cristiano Ronaldo each boasts a contender for the world's best player.
They reached their summit meeting on May 27 in Rome in very different ways - United hammering Arsenal 4-1 on aggregate but Barcelona going through on the away goals rule after their extraordinary 1-1 draw at Chelsea on Wednesday.
Barcelona's faith in quick, short passes was taken to the brink as, after failing to score in the goalless first leg at the Nou Camp, they had gone another 92 minutes without even threatening a goal at Stamford Bridge.
However, Andres Iniesta's stunning late strike, a remarkable piece of technique as he squirmed his body into shape to hit a ball coming awkwardly across him, eventually gave them their reward and a place in the final that most neutrals would have been hoping for.
"We won't change our approach, which is take the ball, move the ball and try to create chances," Barcelona coach Pep Guardiola said after the game.
"I think it is going to be a nice final because we are going to attack, we are going to score goals and not sit back and they know that.
"Manchester United are the reigning champions and they are an unbelievable team with a coach with huge experience. But we are Barcelona."
Guardiola, enjoying a dream first year in charge of the club he graced for 11 years as a player, said he would spend the next three weeks studying videos of United, including last year's 1-0 aggregate semi-final victory over his team.
DISTRACTIONS
However, like United, he has one or two distractions.
"We need to close out the league campaign, try to win the King's Cup next week against Bilbao and then think about the final in Rome," he said.
United, with the World Club Championship and League Cup already in the bag, are also closing in on the Premier League title but it is the Champions League that drives manager Alex Ferguson on.
His team have won the European Cup three times in all, twice under his stewardship, while Barcelona have taken it twice -- once when Guardiola was a player.
For such mighty clubs those returns pale alongside the nine of Real Madrid and five of Liverpool, the teams' fiercest domestic rivals.
Both clubs will go into the final shorn of players through suspension.
United will be without Darren Fletcher, wrongly sent off in the latter stages of Tuesday's second leg win over Arsenal, while Barcelona miss Daniel Alves and Eric Abidal.
Alves picked up a yellow card on Wednesday that brought a final suspension while Abidal was sent off, arguably also harshly, for bringing down Nicolas Anelka in a "last-man foul".
"They are happy we went through but it is tough for them because they will miss the final," Guardiola said of the unfortunate duo.
"I spoke to Daniel before the match and told him that he had to control his emotions or he would not be i
