Arsenal - 1 Chelsea - 2: Vengeance is seldom as elevated as this. With three minutes to go, Wayne Bridge finished beautifully after an exchange with Eidur Gudjohnsen to complete a comeback that sends his team to the Champions League semi-final by ending Arsenal's run of 17 matches against them without defeat.
They might also have scored moments before when Ashley Cole cleared a Gudjohnsen shot from the goal-line and success was theirs by right on this tense evening.
A contest of this intensity can raise spectators from their seats and footballers from the treatment tables. Ashley Cole, Freddie Ljungberg and Jose Antonio Reyes were all in the Arsenal side even though it is just a day or two since they looked stricken. Curiously, it always felt as if the trio were needed to rally round in a crisis.
That should not have been the case, since their away goal in the 1-1 draw at Stamford Bridge was a palpable advantage in this tie, but Arsenal were the more nervous team. They had just come from the FA Cup defeat by Manchester United and were trying to go to the first Champions League semi-final in their history. The memories and the hopes both put them on edge.
The situation was not conducive to the relaxation Arsenal need if they are to settle into their tempo. Arsène Wenger's players were jumpy and only showed rapport when the interval was in sight, yet that was sufficient to put them in front.
With stoppage time in progress, Robert Pires struck a pass to the right. Lauren crossed deep and Thierry Henry headed down towards the edge of the six-yard line, where the outstretched foot of Ljungberg pushed the ball into the path of Reyes. John Terry tried to reach him but could not stop the Spaniard from tucking a shot through the legs of the goalkeeper Marco Ambrosio.
For all Arsenal's innate talent, a goal had only twice been feasible until then. Henry side-footed a deft Reyes flick wide in the 20th minute and Robert Pires headed into the side-netting from a Cole cross 19 minutes later. At that stage the visitors must have been satisfied with a pell-mell match about which they were more optimistic than their manager had admitted.
This match carried a heavy significance that pressed even the unpredictable Claudio Ranieri into orthodoxy. He retained the starting XI that had beaten Tottenham 1-0 on Saturday - only the second time he has spurned an opportunity to tinker this season - pairing Jimmy-Floyd Hasselbaink and Gudjohnsen together in attack. A record of eight wins and a draw in the nine previous occasions when they have been fielded together this season indicated they were Chelsea's most effective pairing.
That meant Adrian Mutu and Hernan Crespo, who cost the club a total of almost £33 million, were on the bench, but this was not the time for inflexible pride from a coach. Whether or not Chelsea, unable to find a suitably august replacement, are preparing grudgingly to keep Ranieri, he had his opportunity to enhance his reputation in the football community at large.
Chelsea could envisage their penchant for long, hard struggles reaping a reward. They had, for instance, already won 13 games in all competitions this season by a 1-0 margin, the latest at White Hart Lane.
They had a settled air, combined with the abrasiveness that had quick bookings for William Gallas and Hasselbaink as a by-product.
Chelsea ought to have scored the opener after 22 minutes. A Bridge pass and Gudjohnsen's lay-off let Damien Duff accelerate. He went past Kolo Touré inside the penalty area but let himself be distracted by Edu's bid to recover and fired wide.
There was no cause for the visitors to be despondent when they found themselves lagging. A goal had been a necessity and their aim, in some respects, was barely altered. Ranieri's simple adjustment was to add to their quantity of attackers by replacing the trenchant Scott Parker with the winger Jesper Gronkjaer.
Arsenal rarely convince when guarding a 1-0 lead and their covering had a frantic tone as the second half got underway. It was no shock that the visitors should be on level terms in the 51st minute, even though Jens Lehmann ought to have prevented the equaliser.
Duff crossed from the left and Edu's clearance was met with a potent 25-yarder from Claude Makelele. The ball was swerving menacingly, but the German goalkeeper would have been expected to beat it wide. Instead, Lehmann padded it into the goalmouth, where Lampard pounced.
The midfielder was very nearly to score again within seven minutes. Pires tried to burst out from his own penalty area, but the ball ran away from him and into the stride of Lampard, whose first-time effort went marginally wide with Lehmann beaten.
Arsenal had the majority of possession, but not the benefits that normally accompany it. So resolute was the Chelsea back four that Ambrosio, a 30-year-old goalkeeper who has made perhaps a couple of dozen first-team appearances in his whole career, was not much tested until Reyes made him parry at full stretch in the 72nd minute.
There was a tip-over from a Touré 35-yarder soon after, but Chelsea's own quest for a second goal was the equal of Arsenal's in conviction. An alarmed Wenger even took the remarkable decision to replace Henry with Dennis Bergkamp, a decision that he was to regret as his side forlornly chased the game in the final minutes.
ARSENAL (4-4-2): Lehmann; Lauren, Touré, Campbell, Cole; Ljungberg, Vieira, Edu, Pires; Reyes, Henry (Bergkamp 81). Subs not used: Stack, Keown, Wiltord, Gilberto, Clichy, Kanu. Booked: Lauren.
CHELSEA (4-4-2): Ambrosio; Melchiot, Gallas, Terry, Bridge; Parker (Gronkjaer, h-t), Makelele, Lampard, Duff (Cole, 82); Hasselbaink (Crespo, 83) Gudjohnsen. Subs not used: Sullivan, Mutu, Geremi, Huth. Booked: Gallas, Hasselbaink, Cole.
Referee: M Merk (Germany).
