The Black Cats fell behind to an Aleksandar Kolarov free-kick after just five minutes before Sergio Aguero and James Milner piled on the misery.
And the Belgium international has admitted that his side can have no complaints over the nature of their loss to Roberto Mancini's side.
"They really wanted to win the game and played really well," he told the club's official website. "We had some chances on the counter-attack but not enough to threaten the opposition, whereas they created a lot of opportunities.
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The 24-year-old shot-stopper went on to cite his side's concession of an early goal as the key moment of the match.
"In games like this you want to keep it goalless as long as you can, but by conceding early it meant a tough game got even tougher," he added.
"After going ahead early City pressed us really high up the pitch and created lots of chances."