Manchester City pulled off the enormous task of giving the Spanish champions a goal head start and not only beating them 3-1 but establishing a superiority which wasn't quite reflected by the scoreline.
Lionel Messi's sublime early counterattack goal – end-to-end perfection – led to a period of attacking domination from which Barcelona failed to profit.
Josep Guardiola's team then not only equalised before the break through İlkay Gündoğan, when Barcelona erred in defence, but added a sublime Kevin De Bruyne free-kick after it, plus a second from the outstanding Germany midfielder to seal a memorable victory.
Barcelona may reflect on André Gomes hitting the bar when in front of an open goal, but the truth is that this was a regal, high-power, hugely intense City showing from which they too might have scored more.
Key player: İlkay Gündoğan (Man. City)
De Bruyne was a contender with a brilliantly struck free-kick, Raheem Sterling put in an impressive shift, yet Gündoğan takes the honours. He was as influential as anybody in City winning the midfield battle as they turned this contest around. Indeed it is fair to say Sergio Busquets will have few evenings as uncomfortable as this during the remaining six months of the season. On top of that, of course, were his two goals, as this impressive athlete showed the hunger and anticipation to be in the right place in the Barcelona box to sweep the ball home.
Guardiola in his programme notes wrote about changing the City fans' attitude towards this competition. Well, this end-to-end thriller was a game to seduce any football lover and the home supporters must have thrilled at their side's response after falling behind. Yes, they had to roll with the punches during a half-hour of Barcelona supremacy but when they hit back, they did everything with such terrific speed and precision, summed up by the way they opened the Catalans up for the first and third goals.
Football at its most thrilling
Remember when Luis Enrique said after the Camp Nou game that he was exhausted just from the effort it took to plan and counter-plan against Guardiola? Well, this was the on-pitch version. The watching audience at the match and the millions around the world, saw something wonderful, intelligent and enthralling.
Just stop to think for a moment what it costs footballers to perform like this. All of us talk about fitness, injuries, and the stamina needed to last a long eight-month campaign. However, try to imagine the mental agility, psychological strength and determination required to produce non-stop, high-quality thrust and counter-thrust football like this across 90 lightning-fast minutes. Football at its most thrilling, but also its most testing for these world-class entertainers we know as footballers.
Simon Hart, Manchester City (@UEFAcomSimonH)
City have been waiting for this moment for so long and it felt worth the wait. There were fireworks outside the ground which lit up the night sky as the players warmed up. But City supplied the real show as they finally got the better of Barcelona at the sixth attempt, and underlined what Guardiola has already brought to the blue half of Manchester. The questions about their defending can wait for another day; this was a real night to remember.
Graham Hunter, Barcelona (@UEFAcomGrahamH)
So here's a clue for Barcelona's rivals from here on in. For years it was they who would play at an infernal tempo – shaking, rattling and rolling opponents into mistakes, into playing quite the contrary to their game plan. Right now things have changed a little. Drop your guard in the UEFA Champions League and this strike force will punish you. Give the 'newbies' like Samuel Umtiti, Gomes and Lucas Digne time to think and they will look five-star. But City performed the enormously difficult task of producing high-tempo, relentless, risky creative football and not only made fewer errors than their visitors but gave them a goal start and still knocked them right out of their stride.