“Of course (I was worried). But like the Newport game two years ago, we worked, suffered, tried different systems and were there at the end and our quality was the difference," Guardiola said.
“But a big complement to our opponents and I said that to Michael (Duff). They have a fantastic team who defend so compact and they fight as one.
“We are happy to win this type of games, in this competition – we know what can happen all around the world and in Europe when smaller teams can knock bigger ones out and we knew it.
"I know from my experience when we played Newport two years ago and we won in the last minutes of the second half were tough and against Wigan knocked us out so we know the FA Cup and that's why it is nice that every team can beat anyone.
“But it is about our response in 90 minutes - at 1-0, I didn't have any regrets about the way we were playing or behaving.
"And fortunately the talent from the cross from Joao the exceptional finish from Gabriel and Phil – the goals were excellent.
“I was very happy with the reaction of the players."