Barnsley head coach Paul Heckingbottom bemoaned the 13-minute first-half spell in which the hosts raced into a three-goal lead to set up victory for home manager Lee Johnson against his former club.
“In that first 10 minutes, we both hit the bar and there was nothing in it,” said Heckingbottom said. “But the first goal changed the nature of the game.
“When we look back over that spell, every chance they created there was something fundamentally wrong. Our problem is that even with 11 new players we are still way short of where we want to be.”
Bristol strolled to a comfortable 3-1 opening-day victory as Bobby Reid and Famara Diedhiou put brittle Barnsley to the sword at Ashton Gate.
Without the departed rising Chelsea striker Tammy Abraham and play-maker Lee Tomlin, Johnson’s side appear to have found new blood up front in the form of Senegal striker Diedhiou, a £5.3m club-record addition from Angers in France, and Reid.
The 24-year-old local lad was pushed into a more advanced position during pre-season and it worked to good effect.
Against opponents who have sold key personnel in the summer and might well be heading for a relegation battle, Reid scored twice and set up Diedhiou for a debut goal inside the opening half-hour.
Barnsley managed a stoppage-time consolation through substitute Ryan Hedges, but utter humiliation was only prevented by the Tykes’ Welsh goalkeeper Adam Davies.
Bristol City: Fielding, Pisano, Wright, Hegeler (Flint 82), Bryan, Brownhill, Pack, Smith, Paterson (O’Dowda 73), Diedhiou, Reid (Engvall 81). Unused substitutes: Magnusson, Vyner, O’Neil, Lucic.
Barnsley: Davies, McCarthy, Jackson, MacDonald, Yiadom, Potts (Hedges 63), Moncur, Joe Williams, Mowatt, Ugbo (Payne 79), Bradshaw (Hammill 46). Unused substitutes: Townsend, Pinnock, Brown, Bird.
Referee: A Davies (Hampshire).