Manchester City needed a late Sergio Aguero winner to claim a 2-1 advantage from the first leg of their Carabao Cup semi-final against Bristol City.
The runaway Premier League leaders were given a stern test by the Championship side and fell behind to a Bobby Reid penalty after 44 minutes at the Etihad Stadium.
Pep Guardiola's men created numerous chances in a strong response but, after Kevin De Bruyne's well-worked 55th-minute equaliser, they had to wait until substitute Aguero headed in a Bernardo Silva cross in injury time.
The Robins, for whom goalkeeper Frank Fielding was outstanding, deserved to take something from the game and their goal may give them some hope for the return at Ashton Gate.