Martyn Waghorn pulled a goal back for the Blues four minutes before half-time but Bristol City had a 2-1 lead at the break, Josh Brownhill and Famara Diedhiou having netted their goals.
Mick McCarthy unsurprisingly initially named the same XI which beat Sunderland 5-2 on Tuesday evening.
However, Tom Adeyemi suffered an injury in the warm-up and Tristan Nydam replaced the former Cardiff City man alongside Cole Skuse in the deeper midfield role.
McCarthy again started with Waghorn, David McGoldrick, Bersant Celina behind lone out-and-out striker Joe Garner.
Central defender Adam Webster was back on the bench after recovering from his ankle injury, while keeper Dean Gerken also returned to the 18 after missing the Black Cats thrashing due to a hip problem.
For Bristol City, who went into the game seventh, one place and one point behind the Blues, midfielder Marlon Pack, who has already amassed five bookings for the season, was replaced by Brownhill in an otherwise unchanged side.
The visitors took the lead with the first shot of the game. Callum O’Dowda cut the ball back from the right to Brownhill, who hit a shot from the edge of the box which hit Nydam in the face and deflected past the wrong-footed Bartosz Bialkowski to his right.
The Robins created another opportunity in the 10th minute with Famara Diedhiou sent away with only Luke Chambers between him and the goal but the Blues’ skipper make an important challenge.
Bristol City continued to have most of the ball and might have done better with an opening in the 13th minute but Bobby Reid eventually shot powerfully from a tight angle on the right against Jonas Knudsen with the ball ricocheting back somewhat painfully into his own face.
On 17 Knudsen was shown the game’s first yellow card for a foul on O’Dowda after the Irishman had got away from him on halfway. The Danish international subsequently underwent treatment before continuing.
The visitors were inches from doubling their lead in the 21st minute when Reid cut in from the right and smashed a powerful shot which was goalbound until Jordan Spence slid in and got enough on the ball to deflect it on to the bar. Without Spence’s touch the ball would certainly have ended up in the net.
The Blues finally started to cause the Robins backline some problems in the 22nd minute when Skuse sent Garner away towards goal but the former Rangers man was crowded out and his shot looped into the air off a defender
A minute later, Waghorn was sent away down the right by McGoldrick and cut the ball back to the edge of the area for ex-Robin Skuse, whose shot was blocked.
After a slow first 20 minutes the Blues were starting to make an impact and on 27 Garner fed Celina not too far outside the area and the on-loan Manchester City man hit a powerful shot just past Bristol City keeper Frank Fielding’s right post. Moments later, Joe Bryan was booked for wild lunge on Garner.
But the visitors quickly got back on top, Jamie Paterson wasting an opportunity when he cut in from the right and smashed a shot which flew out for a throw.
However, on 31 Paterson created his side’s second goal of the game. The former Nottingham Forest man crossed from the left and Diedhiou rose above the diminutive Nydam and nodded down and into the corner of the net.
The Blues carved out what was their best chance of the half in the 36th minute when Iorfa cut the ball back to Celina from the right and the Kosovan international diverted towards goal but Fielding saved sharply.
Bialkowski gathered low to his left from Paterson on 40, then a minute later the Blues pulled a goal back.
After good work from McGoldrick, the ball ran out to Knudsen on the left and the Danish international sent in a low ball which the on-rushing Waghorn slammed into the net off the underside of the bar.
Garner and Aden Flint clashed soon after the restart, the City defender appearing to stand on the Blues frontman following a challenge on halfway. After speaking to both players after the ball had gone out of play referee Simon Hooper took no action.
Moments later, Flint’s central defensive colleague Nathan Baker caught Garner with a flailing arm as they battled for an aerial ball, Hooper awarding Town a freekick but surprisingly not showing the former Aston Villa man a card.
Bristol City threatened again in the final moments of injury time, Flint heading Paterson’s left-sided corner into the ground and Bialkowski tipping it over the bar.
Soon after, referee Hooper brought an entertaining half to a close with the Robins deserving their lead.
Lee Johnson’s men had controlled the game for the most part and could well have scored more than their two goals, Spence having got in a vital touch to divert Reid’s shot on to the bar.
Town had started slowly and didn’t really get going until the 20-minute mark when they began to have more of the ball and create one or two chances.
Waghorn’s goal has given the Blues a lifeline ahead of the second half but their performance will have to be better than their first-half display if they’re to get anything out of the game.
Town: Bialkowski, Iorfa, Chambers (c), Spence, Knudsen, Skuse, Nydam, Waghorn, McGoldrick, Celina, Garner. Subs: Gerken, Webster, Connolly, Ward, Sears, Bru, Kenlock.
Bristol City: Fielding, Bryan, Flint, Wright (c), Baker, Smith, Brownhill, Diedhiou, O’Dowda, Reid, Paterson. Subs: Steele, Taylor, Woodrow, Eliasson, Magnusson, Hegeler, Leko. Referee: Simon Hooper (Wiltshire).