A cruel red card halted a rampant City display in its tracks as visitors Brentford prospered from a big decision at Ashton Gate.
The newly-promoted hosts flew out of the traps, taking a second-minute lead through Jonathan Kodjia.
Alan Judge’s quick-fire equaliser did nothing to stem the flow of City attacks, and Aaron Wilbraham glanced home from a corner to deservedly retake the lead.
But the pivotal moment would arrive ten minutes before the break when Luke Freeman was dismissed for a high foot that unintentionally caught Brentford’s Harlee Dean.
City were unable to hang on until the interval, as Derrick Williams put through his own net, before Andre Gray and Philipp Hofmann added second-half goals against a physically spent home team previously well on top.
Steve Cotterill welcomed Joe Bryan back from injury after the Bristolian missed the midweek Capital One Cup tie at Luton Town with a knee problem.
That meant no starting place for Callum Robinson, scorer of City’s only goal at Kenilworth Road, but there were home debuts for Ben Hamer in goal, Ryan Fredericks at right wing-back and Kodjia up front.
The brand new South Stand did not take long to have its foundations tested as City roared into an early lead.
It was the familiar sight of a long-haired Luke who was the architect – not Freeman this time, but room-mate Ayling who showed impressive quickness of feet, vision and composure to pick out Kodjia in the box.
The summer signing still had work to do, but his first touch was good and his second decisive – a low right-footed shot from 12 yards that flashed past David Button at his near post.
The new-look Ashton Gate was bouncing and the players were responding. There was a fervent tempo to the early exchanges, with Marlon Pack going into the book for the second of two overzealous slide tackles.
But City’s lead would last only seven minutes, as striker Gray escaped the home backline and saw his attempted chip parried by Hamer only into the path of Judge, who could afford to take a touch before making absolutely sure from close range.
It was remarkably end-to-end stuff. Kodjia’s pace took him away from the Brentford defence before James Tarkowski recovered just enough to put him off his stride.
Next to go close was Wilbraham, turning in the box and dragging a shot just past the post, before City had a lucky escape of their own when Williams cleared off his own goal-line after the Bees had swarmed down the City left.
But, as the saying goes, the best form of defence is attack and the red shirts kept pouring forward.
Bryan was having an unbelievable first half against the helpless Alan McCormack, who had no answer to the youngster’s pace and power.
His end product wasn’t bad either, picking out Wilbraham for a chance he ought to have converted, only for Button to stand tall and save when either side of the keeper would have beaten him all ends up.
But the City skipper was not to be denied, glancing Marlon Pack’s resulting corner inside the far post with the slightest of very deliberate touches.
Such was the nature of the action, it never looked like being the end of the scoring.
The ever-adventurous Ayling was involved again down the right on 27 minutes, latching on to a Freeman pass and pulling the ball back invitingly for Kodjia, who should have at least hit the target in firing over the bar.
It had been a superb exhibition of high-tempo attacking football from the hosts, but City’s world would turn upside down when Freeman saw red ten minutes before the break.
When an innocuous high ball dropped midway between the midfielder and Dean, Freeman’s raised boot made contact with the defender and, after a long delay, he was facing the long walk back down the tunnel at the Atyeo end.
There could be no question of any intent on the part of Freeman, whose eyes were fixed on the ball, but referee Keith Stroud deemed the challenge dangerous. For a point of reference, think Nani for Manchester United against Real Madrid in 2013.
Suddenly City had a containing job to do, as Wilbraham dropped back to make up the numbers in midfield through to the interval, by which time Brentford were level again.
Another cross from the left seeking out Gray was flicked on its way before squirming past the unfortunate Hamer, seemingly deceived by his own player as Williams got the final touch.
Understandably, there was a relative air of calm about proceedings after the break, with City’s gung-ho approach no longer a sustainable tactic given their numerical deficit.
But Cotterill’s men remained an attacking threat and had a golden chance to go in front for a third time when Bryan sent Williams on the overlap, whose cutback for Kodjia deserved a better finish.
It would prove a pivotal moment, as Brentford attacked in similar style only to find the net when McCormack raced to the byeline and picked out Gray, who beat Hamer from 15 yards with a crisp strike.
The Bees had been let off the hook having been under relentless pressure against City’s full complement, and Hofmann’s well-placed shot on the turn would prove the final nail in the coffin.