City won 3-1, with Jeremy Doku, Omar Marmoush and Rayan Cherki scoring for the visitors after Goncalo Franco had opened the scoring for Swansea.
“I’m happy for Omar because strikers need goals and for his confidence it will be important, but he’s been injured a long time and of course can play in the position from Erling,” said Guardiola afterwards.
“Erling is important, but of course we know we need them both and having (Omar) back is so nice.
“We have incredible deliveries with Phil and especially with Rayan Cherki and Nico Gonzalez who is day by day getting better.
“And is now fundamental for us. But all of them, the ones who came off the bench, John (Stones), Josko (Gvardiol), Phil (Foden), everyone was really good.”
On Swansea, Guardiola said: “They started really well. I think we started with a really good tempo. Really good.
“We were not flat, but they were better. So in this competition the first minutes the home team they make a boost, and they deserved a goal.
“They played impressively, I would say. But after 20/25 minutes we take the game.
“We arrive, we had our chances and the second half I was really impressed with attack against 10 players in that position, everyone was there. Everyone was perfect in the right moments.
“We were close to avoid transitions; second half was really good. We had chances, just missed again the last pass, the last shot. Phil in the final third, we didn’t finish, Oscar arrived…
“I don’t know how many times, but I’m really pleased for the game because I know how difficult it is away, and we are in the quarter-finals.”