Not even  Pep Guardiola  can wake Manchester City from their recurring Barcelona nightmare – the one where Lionel Messi plays the uncontrollable bogeyman. For the third time in three visits to the Nou Camp, City emerged beaten, reduced to ten men and picked off by Messi, who treated his old boss to a hat-trick on his first return to Catalonia with his new club.

When Guardiola, Barca’s glorious coach between 2008 and 2012, returned for the first time with Bayern Munich 18 months ago, he was on the wrong end of a 3-0 defeat, but it was worse this time.

Barcelona and Messi were good, make no mistake, but City were masters of their own downfall with each of Messi’s goals coming as a result of the visitors’ failings. A Fernandinho slip led to the first, Messi was left unmarked for his second and only John Stones knows why he froze like a statue when Luis Suarez skipped around to tee up Messi for his third.

goalkeeper Claudio Bravo With goalkeeper Claudio Bravo sent off for deliberate hand-ball – Barca defender Jeremy Mathieu was later red-carded for a wild tackle on Raheem Sterling – City ended up with ten men for the fourth time in five games against Barcelona. And on a night when Guardiola chose to start without Sergio Aguero, everything that could go wrong did go wrong for City until Willy Caballero saved faced with an 86th minute penalty save from Neymar.

Guardiola has not been shy in making big decisions since beginning work at City this summer, as Joe Hart – shipped out on loan to Torino – will testify. Omitting Yaya Toure from the club’s Champions League squad was another surprise move, while the former Barcelona coach has also shown little desire to rush captain Vincent Kompany back into the team, despite the Belgian returning to full fitness. Hart, Toure and Kompany had become a strong unit at the club, with only David Silva and Aguero coming close to matching their importance and standing within the dressing room, but there is now only one boss at the Etihad Stadium and that is quite clearly Guardiola.

No manager would choose to drop Aguero without being as powerful as Guardiola has already become at City, but that was the decision taken and he made no effort to palm it off as the Argentine being rested.

Guardiola insisted pre-match that Aguero’s omission was tactical – ‘I want more midfielders’ – and City’s all-time leading Champions League scorer was benched in favour of a three-pronged front-line of Kevin De Bruyne, Nolito and Raheem Sterling, all of whom were expected to flood midfield when Barcelona had the ball.

Was it bold? Was it risky? Probably both, but the tactic ensured that City were able to trade blows with Barcelona in a feisty first-half.

Messi againMessi’s goal was an example of the Argentine’s brilliance, and it separated the two teams, but City created their own chances and they certainly held their own in between phases of Barca dominance.

City responded well, however, with Guardiola’s team deciding that attack was the best form of defence.

Nolito and Ilkay Gundogan both forced important saves from Marc-Andre Ter Stegen before Stones missed a golden chance on the stroke of half-time when the £47m defender headed wide from six yards.

As much as City were still in the game at the start of the second-half, the magnitude of their task in terms of fighting back to win was summed up by Barcelona’s remarkable record of not having lost a Champions League at the Nou Camp while leading at half-time since Bayern Munich overturned a first-half deficit in November 1998.

So City already had a mountain to climb before Bravo turned it into Everest by giving referee Mazic no option but to dismiss him on 53 minutes.

Three minutes earlier, Samuel Umtiti had gone within inches of doubling Barca’s lead with a header which flew narrowly wide, but Suarez believed he would do what the French defender failed to do when Bravo’s mistake gifted him the ball 50 yards from goal.

Bravo takes too many risks and Barca have clearly come out on top of the deal which saw Ter Stegen stay and the error-prone Chilean move to City.

On this occasion, losing possession to Suarez left Bravo 40 yards from his goal and, when the forward took aim, the keeper handled the ball. It was a clear red card and he was off.

Replacement keeper Willy Caballero breathed a sigh of relief when Messi sent the subsequent free-kick over the bar, but the little forward was only delaying the pain for Bravo’s understudy, as seven minutes later, he made it 2-0 with a low shot from 15 yards after being released by Iniesta.

Pep Guardiola

Having lost Zabaleta to injury, City were now playing with ten men without one of their most experienced defenders and half an hour to see out.

City continued to search for a goal, despite their one-man disadvantage, and De Bruyne and Stones both went close to scoring.

But the final word was left to Messi, who stroked the ball in from six yards on 69 minutes after Stones had been caught out of position before Suarez raced around the back to tee up Messi.

nymerHe would have had four had he taken the penalty he won after being fouled by Kolarov, but Messi handed the ball to Neymar, only for the Brazilian to see his spot-kick saved.

Barcelona never rest, though, and Neymar was determined to make amends, which he did when scoring a fourth after slaloming through the City defence in the 90th minute.

So four games and no wins now for City and Guardiola. It is hardly a crisis, but it is certainly a challenge the most celebrated coach in world football must face to get his team back on track