Pep Guardiola labelled the match ball used in the Carabao Cup “unacceptable” after his side reached the quarter-finals.
City were unable to find a breakthrough against Wolves on Tuesday, needing penalty shoot-out heroics from Claudio Bravo to progress after a 0-0 draw.
Guardiola was unhappy with the Mitre match ball, which is usually used in Football League matches.
“It is not acceptable. The ball was unacceptable for a high-level competition,” the Spaniard said.
“It is too light, it moves all over the place, it is not a good ball. It is impossible to score with a ball like that and I can say that because we won, I’m not making excuses.
“All of my players said, ‘What is that?’ I’m sorry [but the] Carabao Cup is not a serious ball for a serious competition.