The first thing to clarify is that this is really not about revenge. It has been dressed up that way ever since we knew we were getting a repeat of the 2009 semi-final but the truth is Chelsea can take their place in a very long queue when it comes to the list of clubs who have suffered against Barcelona. For Chelsea, it is not revenge that should be driving them on. It is about trying to keep up with the very best, and stopping the gap from growing even wider.
The trauma of Andrés Iniesta's last-minute goal three years ago should have no impact now other than crystallising the sense of apprehension among the Stamford Bridge crowd. Napoli were one thing, Benfica another, but Barcelona are a different proposition entirely. "Not just the in-form team now," as Frank Lampard put it, "but the top team in world football for years." It is not easy to see how they can be beaten over two legs.
That is not to ignore the scale of Chelsea's improvement under Roberto Di Matteo but simply to recognise the illuminating qualities of their opponents. Pep Guardiola's side have reached the last four of Europe's premier competition for a record-equalling five successive years. They are looking to return the European Cup to the Camp Nou for a third time in four seasons and, in the process, they have become an assembly of rare football gifts. What we are seeing from Catalonia is the team of the 21st century. They are, in short, everything Roman Abramovich wanted Chelsea to be.
Di Matteo's summation was that "we need two perfect games". Even then, it may not be enough when the opposition are this refined. Barcelona have accumulated 96 goals in their 33 La Liga fixtures this season, which is more than they managed throughout last season and even more remarkable when you consider David Villa has been out since December with a broken leg.
They also have Lionel Messi, who comes armed with his own avalanche of statistics. Messi's 243 goals for Barcelona are not just a club record but put him equal 13th in the all-time La Liga list. In 211 matches under Guardiola he has scored 201 times. Sixty-three of those goals have come this season, which leaves him only four behind Gerd Müller's record for Bayern Munich in 1972-73. Only three other players have scored more than 60 times in a single season in Europe: Ferenc Deak (66 for Ferencvaros in 1948-49), Henk Groot (64 for Ajax, 1960-61) and Dixie Dean (63 for Everton, 1927-28). Messi has managed it at the age of 24. In his past 15 games he has scored 29 goals and had six assists.
With this kind of artillery it is no wonder the undertone was always in favour of Barcelona when Guardiola and Cesc Fábregas, then Di Matteo and Lampard, took their seats for back-to-back press conferences in the Ron Harris Suite at Stamford Bridge. Lampard was asked at one point whether the Chelsea players genuinely believed they could win when everyone else assumed this was the end of the adventure. One of the final questions for Di Matteo came from a Dutch journalist. "In Holland," he said, "we say every Barcelona game is like a piece of art. How do you describe Chelsea's game?" Di Matteo smiled politely. "We play football."
As underdogs go, however, Chelsea, deserve better than to be patronised when they have won nine and drawn two of their 12 games since André Villas-Boas was moved on. They are also unbeaten in their past five matches against Barcelona. "They don't like playing against us," Di Matteo said. "The way we play is maybe difficult for them. The results in the past show that. We've shown on many occasions we can give them a lot of problems." Lampard also wanted to stress there was no inferiority complex.
"We will have to be at our best because we're playing the best," he said. "We're under no illusions about that. But I like the tag of underdogs. It's just important we don't want to take too much fear into the game. You can talk yourself into fear by talking up Barcelona."
Then we came to Guardiola and his verdict of a Chelsea side sixth in the Premier League, 25 points off the top. "They might not have been very consistent in the Premier League but over two games they're difficult to beat. I'm struggling to see how we'll hurt them, create chances and score."
All the same, this is not a Barcelona side who generally struggle for goals. If Chelsea are to stand any chance they will need to play with great control and structure because if there is one certainty it is that their opponents will have more of the ball. "Take the ball, pass the ball; take the ball, pass the ball," as Guardiola put it. These are games that require phenomenal levels of concentration and organisation for their opponents. After that, Chelsea need to hope that luck is on their side. More than anything, they need the best team on the planet to have a rare off-day. Two, in fact.
"I think it's imperative to play a pressing game," Lampard said. "There's no way you can be passive against Barcelona. We'll have a game-plan to attack them, but the main thing is a sense of urgency in your defenders. When you give Xavi, Iniesta and all the rest – I could go on and on – time on the ball they'll hurt you. So we have to pressure them, in all areas of the pitch."
All very well, except these were the tactics Manchester United employed in last season's final. Barcelona responded with a masterclass that made the winning score of 3-1 feel generous to their opponents. "It is going to need something special," Lampard said. The alternative, once again, is that Abramovich is consigned to the role of jealous observer, quite possibly with his eyes on the away dug-out.