A controversial decision helped Rotherham United extend their marathon unbeaten run and bring a halt to City’s after six matches.
The Millers profited on the hour mark when Frank Fielding was penalised for handling the ball outside his own penalty area, paving the way for James Tavernier to win the game from the resulting free kick.
It was the defender’s second spectacular strike of the day, having opened the scoring inside the first two minutes with a 30-yard shot which flew into the corner.
City were on the back foot throughout the first half, but came to life three minutes after the break when Wade Elliott levelled the scores with a special goal of his own.
However, a much improved performance in the second period was not rewarded as the Robins’ unbeaten month of March came to an end at the final hurdle.
Steve Cotterill revealed before the game he would not be afraid to make changes to the team who took to the field in midweek, despite the thumping 5-0 victory over that followed.
He stayed true to his word, with a midfield swap that saw Simon Gillett replace Marlon Pack in the only alteration, sticking with the adventurous 3-4-1-2 setup which paid such handsome dividends at Ashton Gate.
Rotherham, unbeaten in 14 games, needed no invitation to get on the front foot. When City failed to close down Tavernier 30 yards from goal, the defender summed up the confident mood of the Millers with a rocket of a shot which sailed past Fielding for an immediate opener.
The home crowd were bouncing, sensing a steepening gradient to their upward curve, and their team were responding.
Lively winger Nicky Adams produced a low cross which Alex Revell took off the toe of strike partner Kieran Agard before his shot on the turn was blocked at close quarters by Derrick Williams.
City were struggling to get to grips with Adams, who found another cross, this time of the lofted variety, headed wide by Agard, before his shot from the edge of the box struck Karleigh Osborne.
The Robins had to wait until the half hour mark to register a first force Adam Collin into his first save, as Scott Wagstaff did well to dig out a cross down by the corner flag which Paterson headed on target but straight at the United keeper.
The hosts broke quickly, with Adams again leading the charge and combining with Agard before Richard Smallwood passed up the chance with a weak sidefoot past the post.
There was no doubting who had bossed the half, and Agard threatened to take advantage of some hesitant defending between Williams and Osborne, breezing past both and dragging his shot only inches wide.
Greg Cunningham’s crude lunge on Revell to earn a booking was another sign of the visitors struggling to get to grips with a home team brimming with self-belief.
Cunningham’s burst to the byeline soon after was a much brighter moment, only for his driven cross to fizz across the danger zone untouched.
City’s biggest concern was preventing an extended deficit, and Agard eyed up the top corner with a curling effort which did not miss by much, before Paterson tried his luck in similar fashion – just eluding the angle of post and bar before the whistle.
Having ridden their luck at times in the first half, there was a fresh impetus about Cotterill’s side after the break, as a moment of opportunism from Elliott conjured a brilliant equaliser.
Latching on to a loose ball, the 35-year-old drove towards the penalty area and unleashed an unerring 25-yard shot which seemed to start a yard outside the far post and arced perfectly back inside the upright.
Rotherham were temporarily rattled, perhaps regretting missed opportunities to put the game to bed long before Elliott had his say.
But the pendulum of momentum would swing back in their favour courtesy of a controversial moment which led to the hosts retaking the lead on the hour.
A regulation Fielding kick from his hands looked to have instigated a City counter-attack, only for the assistant referee to raise his flag and signal the keeper still had hold of the ball for a split second after vacating his penalty area.
Much to City’s collective amazement, play was brought back to the 18-yard line for a free kick which Tavernier duly dispatched into the top corner.
It was a sickening blow for the visitors, who responded brightly when Jay Emmanuel-Thomas’ cross escaped Collin before skipper Craig Morgan hoisted the ball over his own crossbar, while Sam Baldock’s skimming centre also threatened an own goal before Rotherham’s Kari Arnason struck a post amidst a goalmouth scramble at the other end.
Emmanuel-Thomas had been quiet by Tuesday’s standards, but still almost produced a trademark wonder goal when he cut inside on to his left foot, only for his rising drive to elude the crossbar thanks to Collin’s fingertip – a touch not spotted by referee Gavin Ward.
It was to prove the striker’s last action, as Cotterill made a triple change with eight minutes to go, introducing Adam El-Abd, Tyrone Barnett and Pack for the closing stages.
But despite plenty of late pressure, City were unable to carve out one more chance to salvage a point as a nervous home team held on.