One man fit and firing on all cylinders is top scorer Sergio Aguero, who struck four of City's 10 goals in their back-to-back cup triumphs to move on to 22 for the season.
The Argentine striker had City's fourth with 73 minutes played and substitute Iheanacho added further gloss in the final minute as he flicked home.
And Aguero revealed last night he is yet to have a conversation with Etihad officials. When he plays at that level, he's unstoppable.
"If Gabriel Jesus is player of the month he's player of the month, I'm sad he's not able to help us and of course the moment he played he helped us a lot". The Chilean had come out of the team after conceding six goals from as many shots across two matches in January.
Asked when Kompany might return, Guardiola said "soon" and that he "definitely" could play a full part in the remainder of the season.
"The performance from Claudio was wonderful. If they keep doing that, it'll give us a great chance".
"What the fans express - I am not here to judge". "When a goalkeeper or striker makes a good performance, it's for the team". Guardiola has rotated between Bravo and Willy Caballero this season.
The City manager decided on his arrival at the club last July that Hart was not suited to a possession-based style of football.
"I don't know what position I will be playing from now on".
"We're trying to build things and first and foremost stay in the Premier League". "He was good with the ball, one against one, two against one".
"We are still in the process to grow". "I have three months to give my best and as I always said, in June it will be seen".
"I decide on what I see, on what is the recent past, on the upcoming situation of the future".
Terriers' boss Wagner watched the game from the stands, courtesy of his touchline ban.
Guardiola has made clear that he would be content to go forward with Bravo and Caballero as his two goalkeepers next season.
Manchester City finally look like they've hit a bit of form after a torrid spell over Christmas which saw they drop out of the title race and have them looking over their shoulder.
"The result was a fair reflection of the game".
"It's extremely important because the FA Cup it's a attractive competition and we want to go as far as possible".