Manchester City eventually broke down Atletico Madrid's belligerent defence and will take a narrow lead to Spain thanks to Kevin De Bruyne's winner.
The team's talisman eventually found a way past Diego Simeone's well organised outfit as Phil Foden proved to be an inspired sub. City's academy graduate was not even on the pitch for two minutes before he set De Bruyne clear to beat Jan Oblak in what was the night's decisive moment.
The clash at the Etihad had adopted a clear pattern from minute one. Atletico sat deep, often camping 11 men behind the ball as City attempted to find a way through. For periods it looked as if their relentlessness would be stifled by the Spanish side as Oblak remained largely untested despite the amount of possession for the hosts - that was until he had to pick the ball out of his own net.
The visitors were working off scraps but remain firmly in the tie as they prepare for the return leg at the Wanda Metropolitano in a weeks time. Here are five talking points from the Champions League clash.
1. A style clash
The build-up to the clash at the Etihad was all about a meeting of two minds with very different philosophies. The game on the pitch depicted exactly that as Guardiola's unstoppable force found themselves up against Simeone's immovable object.
For Atletico possession was an irrelevance. For City they just came and came and came again. The first-half especially saw the home side attacking in waves, camping in the visitor's half as they tried to find the smallest of gaps. Atletico's two forwards worked off moments, which were few and far between.
In the end - and it is only half-time in the tie - attack won the battle, but the war is far from over.
2. Foden provides the spark
City pressed and pressed in the second-half but couldn't find the spark that would unlock a resolute Atletico defence. That was until Guardiola threw on Foden, whose stock seems to rise and rise like few others. The young England star quickly found some room in between the lines and set De Bruyne clear to open the scoring.
Foden starting on the bench came as little surprise such are the options available at City, but he underlined his importance by making an immediate impact as he arrived as part of a triple substitution that saw Jack Grealish and Gabriel Jesus both enter the clash.
3. A similar narrative?
It is over to you Atletico. The LaLiga side were quite content to play on the break and be reactive - but they will not enjoy that luxury in front of their own fans at the Wanda Metropolitano. It will no doubt make for an intriguing clash in Madrid as Simeone's men are forced to come out and play.
That could yet suit City, who had to be patient as they sought a winner at the Etihad. The danger though is that Atletico can play, which is why more people question their defensive tactics. Guardiola spoke pre-match about the attacking capabilities of his opponents, insisting they do not get enough credit.
Atletico needed to force the issue against Liverpool earlier in this season's competition and cancelled out their 2-0 lead in Spain, before eventually losing 3-2. It does serve to highlight though that, when the Spanish side need to attack, they are more than capable, which means we could see a very different game in a weeks time.
4. Buying in
Whatever anyone's thoughts are on Atletico and the tactics they employ - one thing you have to credit their coach and their players with is their willingness to commit to the cause. Defenders, unsurprisingly, often relish defending. But telling Joao Felix and Antoine Griezmann that they won't see much of the ball and they need to do a job for the team is a different kettle of fish.
Credit to them though, given they would no doubt flourish in other teams, they certainly do their bit. The possession stats made for difficult reading for the visitors - but that is nothing new. Griezmann and Felix were feeding off scraps whilst the wing-backs often made runs without seeing the ball. You get no sense however that the player begrudge their roles.
5. The striker debate
City tried and failed to lure Harry Kane away from Tottenham last term. They reclaimed their Premier League crown playing with a false 9 as Sergio Aguero and Gabriel Jesus often watched on from the bench. Guardiola's system paid dividends but the narrative was still that they needed a natural goalscorer.
Their failure to land Kane, in the eyes of some, left them short, although they've still fared well enough this term. Atletico though was another scenario where you questioned whether having a striker would've made the difference. In Guardiola's City side it is a double-edged sword.
With every cross that Jan Oblak claimed it is easy to say that a poacher would've been busting his gut to get across the near post. But it is just as easy to forget that the false 9, in this case Bernardo, coming short to link play allowed the cross to come in in the first place. the short answer seems to be, based on City's exploits over the past 18 months, they'd probably be as effective with a striker as they are without one.
