Gabriel Jesus struck four goals, while Kevin De Bruyne, Oleksandr Zinchenko, Phil Foden, Kyle Walker and Riyad Mahrez were the others to score.
"We didn't expect anything less with the gulf between the two teams, we thought it could have been more", he said.
After setting up Walker for City's eighth, Mahrez completed Burton's misery with a goal of his own, the Algeria worldwide poking the ball past Collins to round out a one-sided semi-final encounter.
Nigel Clough's side travel to the Etihad hoping to cause a monumental shock and take a positive result back to the Pirelli Stadium for the second leg.
Looking Ahead It would take somewhat of a miracle for City to not progress and we can assume that they are guaranteed another League Cup final under Pep Guardiola. Without that competition, if we had just one competition to play in, I could play with the same 11 or same 12. "We didn't do too much wrong, two or three of the goals we could have done more but we didn't too badly".
"We've not gone into any detail with them because that will frighten the life out of them", admitted Clough. "You can not be 'oh, it's Burton" and we did not - that is why I'm pleased.
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For example, an investigation in 2013 found that a staff member had made "inappropriate, sexual statements" about four clients. After the incident, she was "horrified" about his reaction and said that "by law, we are supposed to report things like that".
After closing the gap on Liverpool to four points at the top of the Premier League, they thrashed Rotherham 7-0 on Sunday in the third round of the FA Cup.
Manchester United 9-0 Ipswich Town (Premier League, March 1995): Andy Cole scored five goals as Sir Alex Ferguson's team recorded their biggest Premier League win but the title went to Blackburn Rovers.
"They have the best youngsters in the country at the moment, so whichever team they play has quality". We have to play second leg and we will take it seriously.
"When you arrive in the semi-final stage first you have to respect the opponents and try to know them because we don't know them".
"Big congratulations to Burton for what they have done, they have beaten teams from Premier League and Championship and deserved to be here", he said.
Jesus, left, scores his side's fifth goal against Burton Albion. Non-League Barnet hit the headlines for their incredible 1-0 win away at Sheffield United which saw them reach the fourth round for the first time in over a decade.