Football is at its finest when it makes you feel alive; when for 90 agonising minutes you are put through the wringer, experiencing every possible human emotion before ultimately, somehow, your team prevails.
From personal experience, the Champions League has always been a good source for that fix. Crisp nights under the lights, the cacophonous noise of tightly-packed stadiums, some of the world's greatest players and managers on show simultaneously across the continent - matches that made you want to run out into the garden at full-time and boot a ball around in the pitch dark. You cannot beat it.
Tuesday 8 March, 2005, was a perfect example. With plenty of needle following a war of words in the press, José Mourinho's Chelsea hosted Frank Rijkaard's Barcelona in the second leg of their Champions League last 16 tie.
The Blues had emerged relatively unscathed from a, frankly, turgid first instalment in a raucous Camp Nou -only 2-1 down on aggregate, despite being down to ten men for most of the second half after a questionable red card for Didier Drogba and some Oscar-worthy histrionics.
This was a Chelsea side under a peak Mourinho, strutting towards a maiden Premier League title, and they were at it from the off at Stamford Bridge. The Blues would lead within eight minutes - Frank Lampard dispossessing none other than Xavi Hernández (yes, that Xavi), before releasing Mateja Kežman to square for the wily Eidur Gudjohnsen, whose exquisite first touch afforded him the space to slam home.
Claude Makélélé was fortunate not see red for a high and dangerous tackle on a young Andrés Iniesta moments later, but within another eight minutes it was two, as Lampard gleefully knocked the ball home after Victor Valdés had parried a deflected Joe Cole shot.
If the Blues weren't already in dreamland, Damien Duff would fire them into the next dimension before the 20 minute mark. A three-pass move from back to front saw Ricardo Carvalho find Kežman, who dropped it off to Cole who half-volleyed it through a chasm in the Barça back line for Duff to race through and slot it between the legs of the onrushing Valdés. Cue pandemonium.
World Player of the Year Ronaldinho would inevitably be the protagonist in Barcelona's ill-fated comeback. The Brazilian converted from the spot after a mindless handball from Paulo Ferreira, before providing the match's most memorable moment.
After controlling an Iniesta pass on the edge of the area, Ronaldinho burrowed the right toe of his Nike Tiempo into the Stamford Bridge turf, twisted and turned his foot and delivered the best toe-punt of all time beyond a stunned Petr Čech.
With just 38 minutes on the clock and having been 3-0 down, a resurgent Barça somehow led the tie once more.
A fraught second half was never likely to match the first for goals, and was instead characterised by thumping tackles, fine margins and the sound of the Pierluigi Collina's whistle. Chelsea desperately sought to stay in the game as the attacking juggernaut looked to kill them off, and somehow nab a winning goal themselves.
And nab a goal they did. Minutes after Iniesta had a shot tipped onto the post and Samuel Eto'o had inexplicably skied the rebound, John Terry would rise to meet a corner with less than a quarter of an hour remaining and send Chelsea into the last eight.
Key Talking Point
This a match with needle aplenty, setting the tone for repeat match-ups in the ensuing seasons. Mourinho had infamously accused Rijkaard of visiting the referee's changing room at half-time in the first leg - an allegation that led to death threats for German Anders Frisk, who was forced to retire, and a touchline ban for the Portuguese. But after all the pre-match acrimony, mind games and general s****housery, Chelsea had prevailed.
A19-minute blitz had put them in prime position to progress, even if Barcelona were to come back into the tie. While Ronaldinho's influence diminished in the second half and the Catalan giants looked less and less likely to score, the Blues' defensive and attacking relentlessness delivered them to the next round.
Roman Abramovich had always dreamed of emulating Barcelona's style, spirit and success, but ultimately - but for 20 minutes of outstanding attacking football - Chelsea had won this tie the Chelsea way, coming out on top in a 180-minute war of attrition.
It felt for all the world that this Mourinho side was ready to win the Champions League, but somehow it was not to be.
Chelsea Player Ratings
Starting XI: Cech (8), Paulo Ferreira (6), Terry (8), Ricardo Carvalho (7), Gallas (7), Makélélé (7), Cole (9*), Lampard (8), Duff (8), Kezman (7), Gudjohnsen (7).
Subs: Johnson (7), Huth (N/A), Tiago (6).
Joe Cole is remembered as the Englishman who didn't play like an Englishman; the step-overs, the flicks, the style of play - he seemed as suited to Barcelona's lineup as he did to Chelsea's.
But this was a night where Cole shelved the flair and put in a remarkable shift for his team. While he didn't get on the scoresheet, his relentless work rate led directly to the second and third goals
As others wilted in the second half, Cole was everywhere; tracking back, putting in tackles and still posing a threat in the final third. One his best performances in the blue shirt.
Key Talking Point
Despite Ronaldinho's brilliance, a much-fancied Barcelona were out at the last 16 stage having only returned to the competition that season, with Rijkaard leading a revolution with the backing of club president Joan Laporta. Having signed the likes of Deco, Eto'o, Rafael Márquez and Ludovic Giuly, a resurgent Barça were on their way to a first La Liga title since 1999.
On this occasion, Frank Rijkaard had lost to master mind-gamer Mourinho, falling into the Portuguese's trap and becoming embroiled in the pre-game vitriol. But to say that he would use this defeat as fuel would be an understatement.
The Blaugrana would be back with a vengeance in the following season, exacting revenge on Mourinho's Chelsea at the same stage of the competition with much the same squad, on their way to winning a Champions League and La Liga double.
Barcelona Player Ratings
Starting XI: Valdés (5), Belletti (7), Puyol (6), Oleguer (6), Van Bronckhorst (6), Deco (6), Gerard (6), Xavi (6), Ronaldinho (8), Eto'o (7), Iniesta (7).
Subs: Sylvinho (6), Ludovic Giuly (N/A), Maxi Lopez (N/A).
On this occasion, Ronaldinho's brilliance was not enough to drag Barcelona from the jaws of defeat to a glorious victory.
However, while it may have been in vain, the brilliant Brazilian had provided the abiding memory of this tie; the shimmy, the lack of back lift, the pure brilliance. Arguably among the greatest Champions League goals ever scored, it won't be forgotten any time soon.
His all-round play on the night was a joy to behold, including flicks, tricks, raking cross-field passes and a display of exceptional upper-body strength. A master at work.
Things That Aged the Best
Even at the tender age of 20, Andrés Iniesta was still one of the best players on the pitch at Stamford Bridge. The fleet-footed midfielder would become one of the world's best, going on to win La Liga nine times and four Champions Leagues in an illustrious career.
Just as it did for Chelsea, this season marked the start of the modern era for Barcelona, who would develop into a consistently formidable foe both in Spain and on the continent, first under Rijkaard and then under Pep Guardiola.
Although Chelsea have fallen from Europe's top table, the Blues would win the Premier League in that watershed 2004/05 season and four more times in the years since, as well as finally winning the Champions League in 2012 and a host of other trophies in between.
Things That Aged the Worst
Honestly, what the hell happened to Frank Rijkaard?
Having won La Liga in back-to-back seasons as well as the Champions League in 2006, Barça endured two barren campaigns that would bring the Dutchman's time at Camp Nou to an end and usher in the Guardiola era.
But surely a Champions League-winning coach like Rijkaard would remain at the top of the game? Sadly, no - instead came a sharp descent into obscurity. After he was sacked in 2008, Rijkaard had unsuccessful spells in charge of Galatasaray and Saudi Arabia, before taking a job at a school in Florida in 2013 (?!) and retiring from football management three years later.
In the opposite dugout, Mourinho's career would follow an upward trajectory for a while longer, although his magic touch seems to have deserted him since he was sacked by Chelsea in 2015.
Elsewhere, that beige/sand-coloured Barcelona kit was and is just horrible.
Players You Completely Forgot Existed
For such a bit match, there is strangely plenty of choice for this accolade.
For Chelsea, Mateja Kežman started in the absence of the suspended Didier Drogba in the Serb's one and only season at the club - a nomadic career that would end in Hong Kong.
As for Barcelona, Gerard López was the midfield anchor - a player who had returned to the club from Valencia with a burgeoning reputation in 2000 having come through the famed La Masia academy. 2004/05 would be his last season with the Blaugrana before a move to Monaco as injuries hampered his career.
Oleguer Presas partnered Carles Puyol at the centre of a leaky Barcelona defence. One of Rijkaard's trusted lieutenants, Oleguer made 127 appearances in five years with the first team before departing for Ajax the same summer the Dutch manager was sacked.
Argentine striker Maxi López - who scored in the first leg - was introduced as an 85th minute substitute. Having joined the club in the January transfer window his strike against Chelsea was one of just two goals he would net in 19 appearances before departing for Russia to join government-owned and now-defunct FC Moscow in 2007. Best known for his beef with Mauro Icardi, who's with his ex-wife Wanda Nara.
What Happened Next?
Chelsea progressed to face another European giant in Bayern Munich in the quarter-finals. The Blues would prevail once again in another classic two-legged affair, edging the tie 6-5 on aggregate.
Rafael Benitez's Liverpool would bring an end to Chelsea's memorable run in the semis, with Luís Garcia's infamous 'ghost goal' deciding a tight tussle and propelling the Reds on to perform a miracle in Istanbul.
A case of what could have been for Chelsea, who would have to wait seven long years to get their hands on the trophy.
Barcelona would only have to wait one year themselves, and Pep Guardiola's arrival a few years later would push them to the next level.
Seriously, what happened to Frank Rijkaard?
What's happened to José Mourinho since his heyday?
Why did Barcelona persist with Victor Valdés for so many years?
What would have happened if that 'ghost goal' was disallowed?