Even Rafael Benitez is surprised by Liverpool on occasions. How else to explain his decision to remove Fernando Torres in the 79th minute, and the blissful chaos that followed?
On the back of a 4-4 draw and an aggregate scoreline of 7-5, it seems ludicrous to think of a team throwing in the towel, but that is what Benitez appeared to do when, 3-2 down on the night and with 11 minutes remaining, he withdrew arguably the greatest striker in Europe and introduced the callow David Ngog.
This was a manager at last admitting defeat. This was a manager choosing to concentrate on the league and, with Steven Gerrard clearly struggling, nursing another vital player through what remains of the season. Clearly, nobody had told his team.
Liverpool's response to Torres's disappearance was to score two goals, through Lucas and Dirk Kuyt, and send the game hurtling into one last breathtaking twist, just when such an outcome seemed unimaginable.
Liverpool were ostensibly beaten when they came here. But they gave Chelsea the fright of the season by scoring two early goals, losing the match by conceding three and then being on the brink of winning it back
when Frank Lampard intervened, a final stake through the heart silencing the thrashing red beast and leaving the onlookers drained.
It was a classic, far superior to the game between Manchester United and Real Madrid in 2003, because that began with United two goals behind and they never got within that margin, for all the illusion of a titanic confrontation.
This was different. Liverpool needed to win 3-0 to progress and got to 2-0. Then they needed to win 5-3 and got to 4-3.
Had Torres been on the pitch in that final 10 minutes who knows how Chelsea would have reacted? No blame can be attached to Benitez for his decision, though.
At that stage it is hard to imagine anyone in the stadium, even those who refused to admit defeat in Istanbul, thought Liverpool had it in them to win this game a second time.
Ultimately, given Liverpool's amazing powers of recovery, Chelsea's victory came down to the influence of Lampard.
His two goals, Chelsea's third and fourth, proved the difference. How he was not included in the short-list as one of the PFA Players of the Year is a mystery.
Gerrard of Liverpool is the only player outside the five from Manchester United who is in contention, and Nemanja Vidic, the United central defender, is already favourite.
Lampard's omission, which appeared eccentric, now looks ludicrous given the way he has dragged Chelsea through matches with vital late goals time and again.
Before the match, John Terry, the Chelsea captain, was expressing his astonishment, while Lampard, passing, just shrugged.
His answer came with the two goals that averted disaster - in a sporting sense only - for Chelsea.
With the grim anniversary of Hillsborough to be marked on Merseyside on Wednesday it seems incongruous to think of defeat in a football match as calamitous.
Liverpool know what real catastrophe is and it is not something that comes accompanied by something as trivial as a scoreline.
Yet had Chelsea lost the humiliation would have dealt a blow to the club's pride, mentality and title ambitions from which it would have been hard to recover.
Sir Alex Ferguson, the Manchester United manager, said the threat to his players would come from the winners of this tie, and Chelsea defeated, that would certainly have been the case.
For this reason, while Chelsea may have been the victors and their fightback in the second half further evidence of the inspirational powers of Guus Hiddink, it is Liverpool who deserve the lion's share of the credit, for reviving a game many believed had ended as a contest with the third away goal at Anfield.
Most thrillingly, they did this the simplest way: hitting Chelsea with all they had early on, shocking them with their ambition to rise to this challenge.
'There's only one rule in street and bar fights,' explains Martin Amis through the brazen voice of John Self, the would-be film producer in his masterpiece novel, Money, 'maximum violence, instantly. Don't pussyfoot, don't wait for the war to escalate. Nuke them, right off. Hit them with everything, milk bottle, car tool, clenched keys or coins.'
Benitez may not read Amis but, on this evidence, he certainly knows street fights.
The first half was his car tool assault. What Liverpool did to Chelsea early on exposed the myth of saving your best until last, of leaving something in the tank for later. Amis was right.
Liverpool got all Chelsea had anyway, and every last drop of it was needed to beat them.
No-one will have enjoyed this match more than Ferguson; his two greatest rivals slugging themselves to a standstill.