City dominated from the outset at the Etihad Stadium and although they were made to wait until the 43rd minute for Pablo Zabaleta's opener, the result was rarely in doubt.
Platt, the first-team coach, said: "We're happy with the result and performance.
"I think the goal just before half-time was more than deserved.
"But it doesn't make the second half any easier - you've still got to go out and play, but it just settles you down a bit without the clock running against you.
"They have shown all season it is hard to score goals against them."