BARCELONA • There is not much a manager can do when his goalkeeper makes a complete hash of things, and gets himself sent off, like Claudio Bravo did in the Nou Camp on Wednesday.

The Chilean departed to a standing ovation after a 4-0 thrashing by his old club Barcelona in the Champions League, but from the wrong fans and for all the wrong reasons.

It was a shocking error but as Pep Guardiola watched Bravo disappear past him down the tunnel, it was not just the Manchester City goalkeeper's judgment but his manager's that was bound to be called into question.

The decision to replace Joe Hart with Bravo has been an intriguing one ever since his slightly eccentric debut in the Manchester derby last month, and a harsh glare is back on that big call by Guardiola after this colossal mistake.

It is less a question of whether Guardiola was right to make a change but more if Bravo, 33, is anywhere near being a top-class replacement.

He has great experience, including two seasons at the Nou Camp, but this was an embarrassing return for him as he miscued a clearance then gave away a deliberate hand-ball trying to save himself - and got himself sent off.

With 11 men on the pitch, City were giving Barcelona a few causes for concern. Down to 10 with more than half an hour remaining, they were hanging on grimly as Lionel Messi scored his second hat-trick in three matches in this competition.

Brazil's Neymar completed the rout in the 89th minute, having missed a penalty minutes earlier, to rub salt into Guardiola's wounds.

But the former Barcelona coach was defiant and defended Bravo in a post-match conference. "Until the last day I am a coach I will try to play from the goalkeeper," he said.

"He will learn from that and there will be no change of goalkeeper, it stays the same."

The unexpected dropping of Sergio Aguero to the bench was another strange call.

Leaving out your star striker - arguably the best player in the Premier League, was about as radical as it gets short of not bothering with a goalkeeper.

The hope was that it would make for better pressing of Barcelona.

And for Guardiola, playing with no striker certainly did not mean sitting back, if only for the obvious reason that City did not have a defence capable of withstanding pressure from an attack of Barcelona's extraordinary prowess.

The plan enabled City to create a number of good chances, but the trouble was in stopping Barcelona creating plenty for themselves.

It was a night when there were so many nutmegs that, up in the stands, Gary Neville said he was commentating with his legs crossed.

Barcelona have been averaging four goals per game since they stuck seven past Glasgow Celtic, and they kept up that tally even against a team with City's resources and Guardiola's acumen.

They have a perfect nine points and are five clear of City in Group C.

Barca coach Luis Enrique likened Messi to "a kid in the playground", noting how his star striker played with ease and no pressure despite having just returned from an injury.

"We saw Messi play like a kid in the school playground today," he said.

"Any other player would be shaking (after coming back from injury) but for Messi, it doesn't matter how long he's been out for or how many games he's missed, he has a total understanding of football. Anyone who ever doubts Messi is naive."

At the end of the night, the restless Guardiola was bruised and battered after City was left in a mess by the wonder "kid" and Barcelona.

Now that his Bayern Munich and City teams have been taken apart by Barcelona, he must be wondering if he left perfection behind when he walked out of the Nou Camp more than four years ago.

Celtic lost 0-2 at home to Germany's Borussia Monchengladbach, leaving the Scottish champions bottom of the group with only one point. Manager Brendan Rodgers said sustained investment in the squad is needed to compete against top teams.

THE TIMES, LONDON, AGENCE FRANCE-PRESSE, REUTERS