Barcelona vs Chelsea preview: Can the Blues complete the job? Martin Lipton assesses their chances
So, it comes down to this.
To 90 minutes in the Camp Nou, against the reigning champions.
Glory within reach, the Promised Land within sight. The Champions League, shining bright.
And having come so close, so often, only to feel the desperate, gut-wrenching misery of failure, could this, of all years, be the one when Chelsea fulfil Roman Abramovich's grand ambition?
That Roberto Di Matteo and his Blues travelled to Catalonia on Monday morning as underdogs was unquestioned, even if Barcelona looked to be running on empty as they effectively had their domestic title wrenched from their hands on Saturday evening.
Yet maybe, just maybe, the pain and anguish that so many members of Di Matteo's squad have been through at this stage can help fire them to a night to redefine all that has gone before.
Monaco, in 2004. When Claudio Ranieri gambled it all on a throw of the dice and lost, even though, briefly on home soil, Chelsea found themselves ahead on the away goal.
Anfield, twice, in 2005 and two years later. Ghost goals - strange that Chelsea supporters have gone silent over that one after Wembley, but there you go - and penalty shoot-out misery.
Then, on the one occasion when they did get past the semi-finals, more torture from 12 yards in Moscow, the face of John Terry a study in utter dejection.
And, last time, also against Barcelona, the enduring spectre of Tom Henning Ovrebo, a night that should have ended in glory but instead, thanks to one swing of Andres Iniesta's right boot, died in anger, outrage, despair.
At Stamford Bridge last week, Chelsea rode their luck. Then again, if you are going to beat Barcelona, you probably have to.
There were four or five clear-cut chances, all squandered. Moments of near-paralysis at the back, when it looked as if Lionel Messi, Iniesta, Cesc Fabregas, Alexis Sanchez, Pedro or Sergio Busquets HAD to score.
But through it all, as Gary Cahill and John Terry matured into a top-class central defensive pairing in the space of 90 minutes, as Ashley Cole showed his enduring qualities, Petr Cech too, Chelsea held firm, retained parity, chiseled out the priceless advantage, saw it over the line.
Now, though, the ultimate test. Messi and Co again, on their home turf.
With 88,000 Catalans inside the cathedral - and most of Europe outside it - urging a Barcelona victory.
With the knowledge that the Turkish referee will have to show more character than most not to fall victim to the con-jobs that will go on, from Busquets and Dani Alves in particular, all night.
It will take something special, no question.
But Chelsea have now gone six games unbeaten against Barcelona. Few teams can match that and a seventh will ensure their passage.
Jose Mourinho, doubtless, will look to remind everybody that Barcelona never beat Chelsea when they keep 11 men on the pitch.
Even a single goal defeat - and, remember, Chelsea have scored first in all of their 11 Champions League games so far this season - would be enough.
That, of course, is easier said than done. Barca have more in their locker than just about anybody else, although it did not exactly look that way against Real Madrid.
Chelsea will have to demonstrate everything they showed in the first leg and more.
If they lose focus, concentration, for a second, they will probably suffer. Nobody is more adept at taking advantage of the smallest mistake than Pep Guardiola's side.
Di Matteo, too, must decide his team.
Ramires did such a great stint on the left, preventing Alves making his trademark runs and, of course, getting in behind his fellow Brazilian to set up Didier Drogba's strike, that it seems hard to believe he will not be asked to do the same job on Tuesday.
But Juan Mata's unwillingness to work back on the right last week was a key contributor to the problems faced by Branislav Ivanovic.
It may be that Di Matteo asks Salomon Kalou, never exactly Mr Popular in SW6 but who always puts the team interests ahead of his own - and perhaps Daniel Sturridge may want to reflect on that? - to perform again, with Mata on the bench.
And even if the initial plan had been to utilise Drogba in the home leg and Torres at the Camp Nou - with Barca more likely to be playing a back three on Tuesday - surely the Ivorian proved his credentials last week.
Real's opener on Saturday highlighted, not for the first time, one of Barcelona's areas of vulnerability. If Chelsea can get the ball in the attacking third and force set-pieces, the right delivery could give them real joy.
All, of course, is conjecture, which can be underpinned - or undermined - when the real business begins.
Chelsea do have the opportunity they wanted, the advantage they craved. Now we will see if, truly, they have what it takes.
Read Martin Lipton on Chelsea every Monday - and follow @MartinLipton on Twitter