• Barcelona talisman Lionel Messi fired his side ahead coolly around Claudio Bravo on 17 minutes
  • Claudio Bravo was sent off for handling outside his penalty area early on in the second half
  • Messi made Manchester City soon pay for Bravo's dismissal as he grabbed his second goal of the game
  • The Argentine completed his hat-trick on 69 minutes with a close-range finish at the Nou Camp
  • Barca substitute Jeremy Mathieu was sent off for two bookable offences in the Group C encounter
  • Neymar missed a penalty late on but quickly made amends with a neat finish to complete the scoreline 
After the second of Lionel Messi's three goals went in, Pep Guardiola ran his hand anxiously across the top of his head. The Manchester City coach looked like a man who was watching his house burn down fully aware that it was he who had left the toaster on.

This, for all Messi's enduring and captivating brilliance, was defeat by managerial error.
City, as Guardiola had hoped, proved a match for Barcelona at times here. It seems strange to say given the score line but City began each half the better and they created several clear chances. 
Lionel Messi wheels away in celebration after netting for Barcelona against Manchester City in the first half
Lionel Messi wheels away in celebration after netting for Barcelona against Manchester City in the first half
Messi gave Barcelona the lead on 17 minutes after capitalising on a City mistake inside their own penalty area
Messi gave Barcelona the lead on 17 minutes after capitalising on a City mistake inside their own penalty area
The Argentine superstar was gifted the opportunity thanks to Fernandinho's (left) unfortunate slip
The Argentine superstar was gifted the opportunity thanks to Fernandinho's (left) unfortunate slip
Messi duly took advantage of the Brazilian's error by coolly rounding former Barca team-mate Claudio Bravo
Messi duly took advantage of the Brazilian's error by coolly rounding former Barca team-mate Claudio Bravo
The 29-year-old (left) was promptly congratulated by his team-mates as they took an early lead
The 29-year-old (left) was promptly congratulated by his team-mates as they took an early lead
Messi gives a thumbs up to his team-mates as they take the lead in this Group C encounter on Wednesday
Messi gives a thumbs up to his team-mates as they take the lead in this Group C encounter on Wednesday
In contrast, City boss Pep Guardiola shows his frustration at seeing his side concede on 17 minutes
In contrast, City boss Pep Guardiola shows his frustration at seeing his side concede on 17 minutes

MATCH FACTS, CHAMPIONS LEAGUE TABLE, PLAYER RATINGS AND MATCH ZONE 

Barcelona: ter Stegen, Mascherano, Pique, Umtiti, Jordi Alba, Rakitic, Busquets, Iniesta, Luis Suarez, Messi, Neymar. 
Subs: Masip, Turan, Rafinha, Alcacer, Digne, Andre Gomes, Mathieu. 
Man City: Bravo, Zabaleta, Otamendi, Stones, Kolarov, Gundogan, Fernandinho, Silva, Sterling, De Bruyne, Nolito. 
Subs: Caballero, Fernando, Aguero, Jesus Navas, Sane, Clichy, Maffeo.
Referee: Milorad Mazic (Serbia)
 
Barcelona's remaining games 
Manchester City (A) - November 1
Celtic (A) - November 23
B. M'gladbach (H) - December 6
Manchester City's remaining games
Barcelona (H) - November 1
B. M'Gladbach (A) - November 23
Celtic (H) - December 6
In their previous visits to the Nou Camp in the Champions League they had not managed to do this. For the first time, this was competitive. It was, for example, only 1-0 to Barcelona at half-time and Luis Enrique had already lost two of his back four to injury.
Ultimately, though, decisions cost City and they were Guardiola decisions.
As a direct result of them, City ended this night thoroughly embarrassed as their run without a win stretched to four games
Strangely, Sergio Aguero was not selected here.
Guardiola explained he wanted strength in his midfield and the football sages no doubt nodded earnestly. But at times football is a startlingly simple game.
The City manager had said he wanted to win this match so surely his team needed a proper centre forward, still needed their best player. As a result of his exclusion, the Premier League team lacked the necessary expertise when their chances arrived. 
Before the match Barcelona fans unfurled several separatist Catalan flags in defiance of UEFA's ban on political symbols.
Before the match Barcelona fans unfurled several separatist Catalan flags in defiance of UEFA's ban on political symbols.
All eyes were on Guardiola pre-match as he returned to the club where he enjoyed success as a player and manager
All eyes were on Guardiola pre-match as he returned to the club where he enjoyed success as a player and manager
Meanwhile his counterpart Luis Enrique was in a relaxed mood ahead of the clash
Meanwhile his counterpart Luis Enrique was in a relaxed mood ahead of the clash
The omission of star striker Sergio Aguero was a surprise omission by Guardiola as he named his City side
The omission of star striker Sergio Aguero was a surprise omission by Guardiola as he named his City side
In his absence it was left to the likes of Raheem Sterling (left) to spearhead the Premier League side's attack
In his absence it was left to the likes of Raheem Sterling (left) to spearhead the Premier League side's attack
Another City attack was thwarted in the opening stages as Gerard Pique (centre) denies Nolito a chance 
Another City attack was thwarted in the opening stages as Gerard Pique (centre) denies Nolito a chance 
And the visitors were given a boost when first-choice left back Jordi Alba was forced off with an injury early on
And the visitors were given a boost when first-choice left back Jordi Alba was forced off with an injury early on
The Spain international was replaced by Lucas Digne as Barcelona were forced into an early substitution
The Spain international was replaced by Lucas Digne as Barcelona were forced into an early substitution
Interestingly, Aguero was not on the field during the pre-match warm up. He did jog down the line early in the second half but was not brought on. Make of all that what you will.
And what now, meanwhile, of Guardiola's decision to jettison Joe Hart back in August?
Claudio Bravo, a goalkeeper purchased for his expertise with his feet, did on Wednesday night what he has done consistently since arriving in Manchester. He made a mistake with his feet.
In presenting the ball to Luis Suarez in the 53rd minute, Bravo was forced to save the resulting shot and was sent off for handling outside the penalty area.
It was a horror moment and it sunk City. Already a goal down to Messi's early strike, City were nevertheless well in the game at that moment but within minutes of Bravo's exit Messi scored again. Then, seven minutes later, he scored again. 
Guardiola watches on from the sidelines as the action continues to gather apace at the Nou Camp
Guardiola watches on from the sidelines as the action continues to gather apace at the Nou Camp
City had a great chance to equalise when Ilkay Gundogan carved through the Barca defence before seeing his shot saved
City had a great chance to equalise when Ilkay Gundogan carved through the Barca defence before seeing his shot saved
The Germany international reacts in disbelief as his brilliant solo run is ended by Marc-Andre ter Stegen
The Germany international reacts in disbelief as his brilliant solo run is ended by Marc-Andre ter Stegen
Barcelona were forced into a second substitution in the first half when Pique was hurt in this David Silva challenge
Barcelona were forced into a second substitution in the first half when Pique was hurt in this David Silva challenge
Silva, who was booked for the foul, apologises to Pique as the latter hobbles off the pitch 
Silva, who was booked for the foul, apologises to Pique as the latter hobbles off the pitch 
Kevin De Bruyne runs at the Barcelona defence as the English outfit go on the attack during Wednesday's encounter
Kevin De Bruyne runs at the Barcelona defence as the English outfit go on the attack during Wednesday's encounter
The 25-year-old was in the thick of the action soon again as he tried to avoid the challenge of Sergio Busquets
The 25-year-old was in the thick of the action soon again as he tried to avoid the challenge of Sergio Busquets
City forward Nolito beats makeshift right back Javier Mascherano to an aerial challenge
City forward Nolito beats makeshift right back Javier Mascherano to an aerial challenge
Just before half-time City had a great chance to equalise but John Stones could only head wide of the far post
Just before half-time City had a great chance to equalise but John Stones could only head wide of the far post
A contest had become a walkover in a matter of minutes and Guardiola's return to his home had turned in to an exercise in self-destruction.
Managers are paid to make big decisions, of course, and occasionally they go wrong. But it is impossible to ignore Guardiola's decisively wretched influence on this game.
Early on, there seemed little alarm. The Aguero question hung in the air from the moment the team sheets dropped but with Kevin De Bruyne asked to operate at the top of City's formation there was a briskness about the visiting team.
Barcelona were not initially at their best. They were sloppy in possession and provided space for City's forward players to operate in. Raheem Sterling was progressive down the right while Ilkay Gundogan was bright in the centre of the field.
There was no Aguero, though. There was no real focal point and after City failed to turn early superiority in to goals, they handed Barcelona the lead. 
Things got worse for City early on in the second half when Bravo was sent off for handball outside his penalty area
Things got worse for City early on in the second half when Bravo was sent off for handball outside his penalty area
Barcelona striker Luis Suarez appeals for handball as his goalbound effort was illegally blocked by Bravo
Barcelona striker Luis Suarez appeals for handball as his goalbound effort was illegally blocked by Bravo
Serbian referee Milorad Mazic shows City's No 1 a straight red card for his handball offence
Serbian referee Milorad Mazic shows City's No 1 a straight red card for his handball offence
Bravo trudges down the tunnel as the Premier League outfit have to regroup with 10 men
Bravo trudges down the tunnel as the Premier League outfit have to regroup with 10 men
Guardiola instructs Silva from a tactical point of view as he looks to re-jig his side following Bravo's red card
Guardiola instructs Silva from a tactical point of view as he looks to re-jig his side following Bravo's red card
The Spaniard's words didn't have the desired impact as Barcelona doubled their lead courtesy of Messi
The Spaniard's words didn't have the desired impact as Barcelona doubled their lead courtesy of Messi
Messi curled home the Spanish club's second of the night with this near post finish from the edge of the penalty area
Messi curled home the Spanish club's second of the night with this near post finish from the edge of the penalty area
He was a picture of happiness following his second goal of the night - taking his tally to five in the Champions League
He was a picture of happiness following his second goal of the night - taking his tally to five in the Champions League
And on 69 minutes the diminutive forward was in a joyous mood again as he completed his hat-trick
And on 69 minutes the diminutive forward was in a joyous mood again as he completed his hat-trick
He grabbed his third goal of the match with this close-range finish past City substitute goalkeeper Willy Caballero
He grabbed his third goal of the match with this close-range finish past City substitute goalkeeper Willy Caballero
The hat-trick was his 37th for Barcelona in a stunning one-man club career to date
The hat-trick was his 37th for Barcelona in a stunning one-man club career to date
Messi's first goal was a poor one. But then others were too.
The Barca No 10 had bustled feverishly down the right in the 17th minute but the move broke down when Pablo Zabaleta tacked Andres Iniesta. As the ball ran free in to the penalty area, either Fernandinho or Nicolas Otamendi could have cleared but one fell over, the other was caught on his heels and Messi eased past Bravo to slide the ball in to an empty goal.
It was a blow for City and for a while Barcelona had them on a piece of string. But it needn't have been fatal as eventually City rallied and ended the first half unfortunate not to be level.
Gundogan was denied by a brilliant Marc-Andre ter Stegen save after a dazzling run and then John Stones, unmarked, headed wastefully wide from a corner.
So at the start of the second half, as De Bruyne twice reached the byline to cross dangerously, City were very much alive. By now, Barcelona had lost Gerard Pique and Jordi Alba to injury.
Time for Aguero? Apparently not and as he watched on from the bench Bravo dashed from his goal to ruin City's evening. 
Despite Barcelona's dominance now, they too were reduced to 10 men when Jeremy Mathieu (left) was sent off
Despite Barcelona's dominance now, they too were reduced to 10 men when Jeremy Mathieu (left) was sent off
The France international, who had come on for Pique, was shown a second yellow card for this foul on Raheem Sterling
The France international, who had come on for Pique, was shown a second yellow card for this foul on Raheem Sterling
Yet Mathieu's dismissal didn't halt the Barcelona juggernaut as they were awarded a penalty, which Neymar failed to convert
Yet Mathieu's dismissal didn't halt the Barcelona juggernaut as they were awarded a penalty, which Neymar failed to convert
The Brazilian shows his frustration after seeing his effort saved by Caballero late on
The Brazilian shows his frustration after seeing his effort saved by Caballero late on
However, the 24-year-old quickly redeemed himself by completing the scoreline with this lovely finish
However, the 24-year-old quickly redeemed himself by completing the scoreline with this lovely finish
Neymar celebrates his strike with Messi and Suarez as Barca move three points clear at the top of Group C
Neymar celebrates his strike with Messi and Suarez as Barca move three points clear at the top of Group C
It proved a harrowing night for Guardiola as he saw his current side dismantled by his former one
It proved a harrowing night for Guardiola as he saw his current side dismantled by his former one
Old friends Guardiola and Enrique embrace at full-time with the two teams due to meet against in Manchester next month
Old friends Guardiola and Enrique embrace at full-time with the two teams due to meet against in Manchester next month
Credit must go to Suarez. The cause he chased was a lost one but he chased it anyway because that's what he does. Had he not been in Bravo's vision, the clearance would have been less hurried. It was still a horrific goalkeeping error, though, and it ended the game.
Messi bamboozled Aleksandar Kolarov to score from 18 yards after Fernandinho was hustled out of possession just after the hour and then slid in his hat-trick goal in the 68th minute after a stray back pass from the hitherto impressive Gundogan played Suarez clear down the left.
Guardiola was hunkered down in his seat by now but will still have seen Messi leave Gael Clichy and Kolarov in a heap as he won a penalty that Neymar allowed substitute Willy Caballero to save. Two minutes later, though, the Brazilian slithered past Otamendi and Stones to make amends and score the fourth.
That was a sumptuous goal but it was merely a knife twist in a wound of Guardiola's own making. Is it possible to be too clever for your own good in football? Perhaps.