Norgaard impressed for the Gunners as they won this third round tie 4-1 on Sunday.
He later said: "In the beginning they were than us and could have gone up twice but then when got the momentum. In the second half we could have made more than four goals.
"The start wasn't good enough. I think we were as prepared as we could have been. In this weather and conditions it is never easy in the cup games and credit to Portsmouth."
On how set pieces helped Arsenal win the game, Norgaard added: "It's important in our games but it's important in any team. Of course we emphasise it a lot but it's a really important part of our game and it's an important weapon of ours. We will keep developing an using it when we need it.
"I think it shows that we are heading in the right direction as a team."