Barcelona put one foot and four toes into the quarter-finals of the Champions League with a 2-0 victory over Manchester City at the Etihad Stadium as the hosts shot themselves in the foot.
A red card for Martin Demichelis for bringing down Lionel Messi nine minutes into the second half tilted what had been an even clash firmly in the Catalans' favour, with Messi picking himself up to score his first-ever goal on an English club ground from the spot.
Prior to that, Barca had had lots of possession but were kept at arm's length by their hosts, who came close through a goalmouth scramble and Alvaro Negredo.
David Silva almost grabbed a late equaliser for them, but the tie was arguably put to bed when Barca's Dani Alves strode through a tired home defence to finish what could be a killer second away goal.
Here are six lessons learned from a night on which City were taught a harsh lesson about life at the summit of European football:
The trouble for Manuel Pellegrini going into this game was that he'd seen too much.
As manager of Villarreal, Real Madrid and Malaga in the past five years, the Chilean will have seen and been on the receiving end of plenty of beatings from Barcelona, and it was certainly a case of being bitten plenty of times and then becoming shy.
City deserve credit for the way they came into the game after barely getting a kick in the first half hour, but in effectively picking two left-backs in Gael Clichy and Aleksandar Kolarov, in leaving Alvaro Negredo isolated up front and allowing David Silva to become swamped in midfield, the manager had put his club on the back foot straight away.
To his credit, he had changed things and injected more urgency into his team before they fell one down, but the chance to land a couple of early blows on Barca had been lost, with City left dependent on chances from set pieces, something that they will be hoping to exploit in the Nou Camp, however tough Dani Alves' second goal has made things now.
As highlighted by 101GreatGoals.com, Twitter had a lot to say about the fact that the often-pilloried Martin Demichelis had been selected by Manuel Pellegrini to go head-to-head with Lionel Messi at the Etihad.
For a while it looked to be a wise decision.
Barca's precise, intricate build-up play during that almost mesmeric first half an hour was stunning to watch at times, but the fact was that Demichelis was in the prime position to watch it. It was all happening in front of him.
Things would have been different had Barca pinched an early goal, then looked to hit City on the break―something that we might still see in the second leg that Demichelis will miss―but given the manner of the game and the pressure that City were happy to invite on to them in the first half, Demichelis was ultimately the right choice to partner Vincent Kompany early on.
The problem was always going to come when Barca eventually got in behind him—and so it proved.
Those 33-year-old legs were never going to catch up with Messi once his compatriot had got half a yard on him, and that is when you are relying on the defender's experience. Stick a leg out and get sent off or allow Messi through?
Demichelis recklessly went for the former.
When he started in that position, you thought that it was merely a stop-gap solution whilst they got other players fit.
But Javier Mascherano has now become so key for Barcelona at centre-back that you'd be forgiven for thinking he's played there for all of his career.
Of course, he doesn't look like a centre-back, especially when he's having to deal with a beast of a centre-forward such as Manchester City's Alvaro Negredo, but the difference in height and stature means that the Argentinean deals with attackers in a different way to natural defenders.
Take his compatriot Demichelis at the other end, where the veteran had the almost opposite problem with the quicksilver Messi.
As he found out to his cost, getting too close to the lightning reactions of the forward would leave him with a problem, but for Mascherano that is almost a necessity.
Getting himself in front of Negredo as the ball dropped loose was key for Barca's mini centre-back, who was able to win fouls and oversee things for his team on a night when they arguably delivered their most impressive performance under Tata Martino.
There are people out there who still believe that "doing it in England" is important when evaluating a player's worth, and so they were appeased 54 minutes into this clash when Lionel Messi effortlessly stroked his penalty into the middle of Joe Hart's goal.
As the Daily Mirror indicated before the game, Messi had played for 807 minutes on English soil before tonight, scoring once and assisting twice.
The fact that that goal was at Wembley in the 2011 Champions League final against Manchester United meant that Messi was still to score at a Premier League venue before tonight, with Anfield, Stamford Bridge, Old Trafford and the Emirates Stadium all failing to be breached by the little master.
He doesn't care of course—a goal is just a goal for the Argentinean superstar, but at least this is one tired and dull statistic that can be put to bed.
Next stop, a wet Wednesday night in Stoke (yawn).
"We'll fight to the end," sang the City supporters as their team entered the final 10 minutes with 10 men and a goal down, and their team certainly didn't disappoint.
The red card for Demichelis was the key element of this tie until Dani Alves grabbed his goal late on, but if City are to take one thing from their first-ever match in the competition's knockout stages, then pride must certainly be it.
Only a fine save from Victor Valdes from David Silva's low volley prevented them from scoring an unlikely equaliser fairly late on, and although they were indebted to a linesman's flag for ruling out the strike from Gerard Pique which would have taken this tie well out of their reach, there was still tangible hope to cling to before Alves struck.
It's a little more hazy now.
However, this is the team that scored three goals in a win at Bayern Munich's Allianz Arena earlier this season, and although that came at the end of a Champions League group phase from which both clubs had qualified, that doesn't need to be remembered when City step out on to the Nou Camp pitch on March 12.
They'll be stepping out there with Sergio Aguero in tow, too.
The latest example of Jose Mourinho sticking his nose in where it wasn't warranted came before this game, with the Chelsea manager―and former Barca assistant for four years during which they didn't win La Liga―claiming that this was "the worst Barcelona side for many years," as seen here on the BBC website.
The comments were picked up and ensured that Mourinho was given a prominent place in the build-up to the match, but, of course ,he was proved wrong. He surely always suspected that he would be.
The Portuguese's latest attempt at the famed "mind games" was supposedly meant to heap the pressure on to City, but it was actually pretty weak and merely served as fodder for his self-made "bad guy" image.
There is nothing wrong with this Barca side, as their performance here and their position at the top of La Liga demonstrate.
And as Mourinho might find out to his cost later in the competition.