City were forced to work hard for their 2-1 win.
"There was a lot to do today but we have to say we were playing against a very quality team," Dúbravka told nufc.co.uk. "We knew it would be a tough game for us, but actually we stood up well and created good moments.
"We played as a team - that's important - and showed a great attitude, great team spirit, but unfortunately for us we didn't score one more goal."
Dúbravka made several saves during the game, including a tremendous triple-stop which saw him deny Fernandinho before keeping out two efforts from David Silva.
"Of course I'm happy for that, but it doesn't mean that much when you lose," insisted the goalkeeper.
"It's good, because that's how a goalkeeper builds confidence and I can build on these kinds of saves, but unfortunately we lost."