Following their opening Champions League win over Viktoria Plzen and Sunday's stunning derby demolition of Manchester United, City maintained their momentum with a comfortable third-round win.
Coyle said: "We worked ever so hard, playing against one of the elite clubs of world football, let alone English football.
"They made 10 changes and their team was probably worth about B£200million.
"There is no getting away from it, we knew it was a tough ask.
"As if their starting line up wasn't enough, I think the three subs they brought on probably added another B£100million to the tally, but I am disappointed to lose by any margin of goals.
"We gave away really soft goals. We can learn from that. It was important we got through unscathed in terms of injury and hopefully we have."