City were 3-1 winners in the FA Cup against the Championship side despite their 20 shots of target, which is unlike the Premier League champions who are normally ruthless in front of goal. The Spanish head coach was not happy with the Mitre balls used in the competition and stated that they are not up to standard.
"The ball in the Champions League is exceptional, the ball in the Premier League is exceptional, this one isn't," he said. "It's difficult to control.
"When you lose it (sounds like) you're complaining, but the ball is not right. In many years it's happened in the FA Cup and Carabao Cup, I know it's a business and they come to agreements.
"You know how many shots went over? Look at other games. Normally the ball goes inside from these shots. "
A Football Association spokesperson responded to his comments and confirmed that all balls used in the competition have been tested to ensure they are up to standard.
"Mitre's Ultimax Pro ball - used in the Emirates FA Cup and all other FA competitions - has been tested in accordance with Fifa testing.
"All footballs in the professional game are required to meet the FIFA Quality pro accreditation, and this ball delivers against all of the testing requirements.
"Alongside Mitre, we understand that preference is subjective, but we're confident that the ball performs well. With over 350 goals scored in the knockout competition so far, it provides an exciting element to such a competitive tournament."
Arsenal boss Mikel Arteta is another top manager who complained about the ball being used in the Carabao Cup after a defeat against Newcastle in the semi-final and now after Guardiola’s comments, an investigation may be needed to stop any further complaints in the future.